The document discusses cell membranes and their role in cellular processes. It covers how membranes are composed of phospholipids and proteins arranged in a fluid mosaic. Membranes allow selective permeability through diffusion, facilitated transport, and active transport. Transport proteins and vesicles move molecules across membranes. The chapter also addresses how cells use ATP and enzymes to drive energetic cellular processes and chemical reactions.
Cellular respiration occurs in three main stages to harvest energy from glucose and produce ATP. Stage 1 is glycolysis in the cytoplasm, which oxidizes glucose to pyruvate and generates 2 ATP and 2 NADH. Stage 2 is the citric acid cycle in the mitochondria, which completes glucose oxidation and generates more NADH and FADH2. Stage 3 is oxidative phosphorylation in the inner mitochondrial membrane, where electrons are transferred through an electron transport chain to generate ATP through chemiosmosis. Fermentation enables some ATP production without oxygen through glycolysis alone.
The document provides an overview of cell structures and organelles, including:
- Light microscopes and electron microscopes allow observation of cells at different magnifications.
- Eukaryotic cells have internal membranes that create organelles, while prokaryotic cells lack these.
- The endomembrane system connects organelles like the ER, Golgi apparatus and plasma membrane to synthesize, modify and transport cell products.
- The nucleus contains DNA and directs protein synthesis, while ribosomes build proteins using instructions from the nucleus.
The cytoskeleton is composed of microtubules, microfilaments, and intermediate filaments that help maintain cell shape and enable cell movement. Microtubules are involved in cell division, shape, and organelle movement. Microfilaments assist with cell division, shape changes, muscle contraction, and motility. Intermediate filaments provide structural support and anchor organelles. Motor proteins use ATP to "walk" along cytoskeletal fibers and transport vesicles and organelles within the cell.
Cytoskeleton - microtubules ,microfilaments and intermediate filamentsBIOTECH SIMPLIFIED
The cytoskeleton is made up of three main filament systems - microtubules, microfilaments, and intermediate filaments. Microtubules are the thickest and made of tubulin, forming hollow tubes that help transport cellular cargo and separate chromosomes during cell division. Microfilaments are the thinnest and made of actin, enabling cell movement and shape changes. Intermediate filaments are in between the other two in diameter and made of various proteins, maintaining cell shape. Collectively, the cytoskeleton gives cells their structure, allows movement, and aids transport within cells.
The document outlines chapter 5 of a biology textbook on membrane structure and function. It discusses:
1) The structure of the plasma membrane, including the phospholipid bilayer and embedded proteins.
2) Passive transport mechanisms like diffusion, osmosis, and facilitated transport that allow molecules to cross the membrane down a concentration gradient without cellular energy expenditure.
3) Active transport mechanisms that require cellular energy to move molecules across the membrane against a concentration gradient.
The document summarizes key concepts about the cell cycle and cell division. It discusses how cell division allows for reproduction, growth, and repair. There are two main types of cell division - mitosis, which produces genetically identical daughter cells, and meiosis, which produces gametes. The cell cycle consists of interphase and the mitotic phase. Interphase includes DNA replication in S phase. Mitosis separates duplicated chromosomes into two daughter cells. Cytokinesis then divides the cytoplasm. Prokaryotes divide by binary fission, with the chromosome replicating and daughter chromosomes moving apart.
The document discusses the structure and function of cells. It describes that cells are the basic units of life and that all living things are composed of cells. It explains that prokaryotic cells evolved first and discusses the structures of prokaryotic and eukaryotic cells. It also summarizes the major organelles found in eukaryotic cells like the nucleus, mitochondria, chloroplasts, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, cytoskeleton, and how they function.
Peroxisomes are organelles found in the cytoplasm of animal and plant cells. They are bounded by a single membrane and contain many enzymes. Christian deDuve first isolated peroxisomes from liver cells in 1965. Peroxisomes oxidize organic substances like fatty acids and produce hydrogen peroxide as a byproduct, which is then broken down by the enzyme catalase. They are most abundant in liver cells, where they are involved in functions like breaking down fatty acids, synthesizing cholesterol and bile acids, and breaking down excess purines.
Cellular respiration occurs in three main stages to harvest energy from glucose and produce ATP. Stage 1 is glycolysis in the cytoplasm, which oxidizes glucose to pyruvate and generates 2 ATP and 2 NADH. Stage 2 is the citric acid cycle in the mitochondria, which completes glucose oxidation and generates more NADH and FADH2. Stage 3 is oxidative phosphorylation in the inner mitochondrial membrane, where electrons are transferred through an electron transport chain to generate ATP through chemiosmosis. Fermentation enables some ATP production without oxygen through glycolysis alone.
The document provides an overview of cell structures and organelles, including:
- Light microscopes and electron microscopes allow observation of cells at different magnifications.
- Eukaryotic cells have internal membranes that create organelles, while prokaryotic cells lack these.
- The endomembrane system connects organelles like the ER, Golgi apparatus and plasma membrane to synthesize, modify and transport cell products.
- The nucleus contains DNA and directs protein synthesis, while ribosomes build proteins using instructions from the nucleus.
The cytoskeleton is composed of microtubules, microfilaments, and intermediate filaments that help maintain cell shape and enable cell movement. Microtubules are involved in cell division, shape, and organelle movement. Microfilaments assist with cell division, shape changes, muscle contraction, and motility. Intermediate filaments provide structural support and anchor organelles. Motor proteins use ATP to "walk" along cytoskeletal fibers and transport vesicles and organelles within the cell.
Cytoskeleton - microtubules ,microfilaments and intermediate filamentsBIOTECH SIMPLIFIED
The cytoskeleton is made up of three main filament systems - microtubules, microfilaments, and intermediate filaments. Microtubules are the thickest and made of tubulin, forming hollow tubes that help transport cellular cargo and separate chromosomes during cell division. Microfilaments are the thinnest and made of actin, enabling cell movement and shape changes. Intermediate filaments are in between the other two in diameter and made of various proteins, maintaining cell shape. Collectively, the cytoskeleton gives cells their structure, allows movement, and aids transport within cells.
The document outlines chapter 5 of a biology textbook on membrane structure and function. It discusses:
1) The structure of the plasma membrane, including the phospholipid bilayer and embedded proteins.
2) Passive transport mechanisms like diffusion, osmosis, and facilitated transport that allow molecules to cross the membrane down a concentration gradient without cellular energy expenditure.
3) Active transport mechanisms that require cellular energy to move molecules across the membrane against a concentration gradient.
The document summarizes key concepts about the cell cycle and cell division. It discusses how cell division allows for reproduction, growth, and repair. There are two main types of cell division - mitosis, which produces genetically identical daughter cells, and meiosis, which produces gametes. The cell cycle consists of interphase and the mitotic phase. Interphase includes DNA replication in S phase. Mitosis separates duplicated chromosomes into two daughter cells. Cytokinesis then divides the cytoplasm. Prokaryotes divide by binary fission, with the chromosome replicating and daughter chromosomes moving apart.
The document discusses the structure and function of cells. It describes that cells are the basic units of life and that all living things are composed of cells. It explains that prokaryotic cells evolved first and discusses the structures of prokaryotic and eukaryotic cells. It also summarizes the major organelles found in eukaryotic cells like the nucleus, mitochondria, chloroplasts, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, cytoskeleton, and how they function.
Peroxisomes are organelles found in the cytoplasm of animal and plant cells. They are bounded by a single membrane and contain many enzymes. Christian deDuve first isolated peroxisomes from liver cells in 1965. Peroxisomes oxidize organic substances like fatty acids and produce hydrogen peroxide as a byproduct, which is then broken down by the enzyme catalase. They are most abundant in liver cells, where they are involved in functions like breaking down fatty acids, synthesizing cholesterol and bile acids, and breaking down excess purines.
The plasma membrane is selectively permeable and allows some substances to pass through more easily than others. It contains phospholipids arranged in a bilayer with hydrophobic tails interacting in the middle and hydrophilic heads facing outwards. Embedded proteins can be integral and span the entire membrane or peripheral and attach to surface. The fluid mosaic model describes the membrane as a fluid structure with phospholipids and proteins able to move laterally. Transport across the membrane can be passive via diffusion, osmosis, and facilitated diffusion or active via protein pumps and requires cell energy. Endocytosis and exocytosis involve vesicle transport across the membrane.
The document summarizes the structure and function of microtubules in eukaryotic cells. It discusses how microtubules are composed of protein subunits that assemble into hollow tubes. Microtubules emanate from microtubule organizing centers and serve important roles as structural supports, in intracellular transport through motor proteins like kinesin and dynein, and in cell division through formation of the mitotic spindle. Microtubules are also the main components of cilia and flagella and enable their bending movements through the motor protein dynein.
The document discusses the key components of the cytoskeleton - microtubules, microfilaments, and intermediate filaments - and how they work together to maintain cell shape, allow movement of organelles and vesicles, transport materials within the cell, and enable cell movement through polymerization and interaction with motor proteins like myosin and kinesin. The cytoskeleton is a dynamic network that forms various structures through accessory proteins and allows rapid changes in cell morphology.
Cilia and flagella are organelles found in eukaryotic cells that are used for cellular transportation. Cilia are short and numerous, while flagella are longer and fewer in number. Both are composed of microtubules in a 9+2 pattern and use dynein arms powered by ATP to bend back and forth, propelling the cell. Cilia movement is coordinated to move cells in waves, while flagella rotation provides smoother movement. Defects can impact functions like respiration and kidney function.
The document provides an overview of metabolism and energy transformations in cells. It discusses how (1) cells extract and use energy to perform work through thousands of chemical reactions organized into metabolic pathways, (2) the laws of thermodynamics govern energy transformations with energy being conserved but entropy increasing, and (3) ATP powers cellular work by coupling exergonic reactions like its hydrolysis to endergonic reactions like transport or synthesis through energy transfer.
This document provides an overview of Chapter 7 from Campbell Biology, Ninth Edition. It discusses membrane structure and function, including the fluid mosaic model of membranes and the roles of lipids and proteins. Key points covered include the selective permeability of the plasma membrane, the fluidity of membranes, membrane protein functions like transport and signaling, and the role of carbohydrates in cell-cell recognition.
The document summarizes key concepts about membrane structure and function from Chapter 7 of Campbell Biology. It discusses the fluid mosaic model of membrane structure, which states that membranes are made of a phospholipid bilayer with various proteins embedded within. Membranes are selectively permeable, allowing some substances to pass through via passive transport mechanisms like diffusion and facilitated diffusion. Membranes regulate the movement of substances in and out of cells.
Describes the plasma membrane in detail, explains the each major component with its functions.
Transport mechanism across the cell is covered with detailed explanation with examples.
by Dr. N.Sivaranjani, MD
The endoplasmic reticulum (ER) is an organelle found in eukaryotic cells that forms an interconnected network of tubules, vesicles, and cisternae. It has two main types - rough ER with ribosomes and smooth ER without. The rough ER is involved in protein synthesis and modification, while the smooth ER performs functions like lipid synthesis and calcium regulation. Newly synthesized proteins are transported from the ER to the Golgi apparatus in vesicles for further processing and modification before being packaged into secretory vesicles and transported throughout the cell. The ER also plays a key role in protein folding and quality control.
The endoplasmic reticulum is a network of folded membranes found throughout the cytoplasm of eukaryotic cells. It was first observed in 1945 by Albert Claude using an electron microscope. The endoplasmic reticulum is divided into two subcompartments: the rough endoplasmic reticulum, which is studded with ribosomes, and the smooth endoplasmic reticulum, which lacks ribosomes. The rough endoplasmic reticulum is the site of protein synthesis and transports proteins throughout the cell, while the smooth endoplasmic reticulum is involved in lipid and steroid metabolism.
Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, water and carbon dioxide to produce oxygen and energy in the form of glucose. It occurs in chloroplasts and involves two stages - the light-dependent reactions where ATP and NADPH are produced, and the light-independent Calvin cycle where glucose is formed. Chlorophyll and other pigments absorb sunlight which is used to power the transfer of electrons and production of chemical energy carriers. Photosynthesis ultimately feeds the biosphere by producing organic molecules and oxygen from inorganic sources.
Cell junctions are multiprotein complexes that provide contact between adjacent animal cells and help hold tissues together. The main types are anchoring junctions, which attach cells to surrounding matrix and each other; gap junctions, which allow direct communication between cells; and tight junctions, which form barriers between epithelial layers. Cell junction molecules like selectins, cadherins, integrins, and the immunoglobulin superfamily mediate cell-cell adhesion through calcium-dependent and calcium-independent binding of domains on neighboring cell surfaces. Cell junctions are essential for tissue structure, cell signaling, and barrier functions in the body.
KEY CONCEPTS
6.1 Biologists use microscopes and the tools of biochemistry to
study cells
6.2 Eukaryotic cells have internal membranes that
compartmentalize their functions
6.3 The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes
6.4 The endomembrane system regulates protein traffic and
performs metabolic functions in the cell
6.5 Mitochondria and chloroplasts change energy from one form to another
6.6 The cytoskeleton is a network of fibers that organizes structures and activities in the cell
6.7 Extracellular components and connections between cells help coordinate cellular activities
This document discusses lysosomes and chaperone-mediated autophagy (CMA). It provides background on the discovery of lysosomes and their structure and functions. Lysosomes contain hydrolytic enzymes and digest macromolecules, cellular debris, and foreign material. CMA selectively degrades cytosolic proteins through binding to a chaperone and lysosomal membrane protein LAMP-2A. Disruption of CMA is implicated in diseases like Parkinson's and cancer. CMA activity declines with age.
A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle.
More than half of all proteins interact with membranes.
The cytoskeleton is a network of protein filaments and tubules that gives cells their shape and allows them to move. It has three main components: microtubules, microfilaments, and intermediate filaments. Microtubules are hollow tubes involved in intracellular transport and cell division. Microfilaments made of actin help with cell movement and shape. Intermediate filaments provide structural support. Together, the cytoskeleton transports vesicles, separates chromosomes, allows muscle contraction, and maintains cell shape.
Biological membranes are thin, flexible surfaces that separate cells and organelles from their environments. They are made up of proteins, lipids like phospholipids and glycolipids, and carbohydrates. Phospholipids are the major lipid component, consisting of a hydrophilic head and two hydrophobic tails, allowing them to form the fluid lipid bilayer structure of the membrane. Membrane proteins can be integral and span the membrane or peripheral and attach to its surface. They perform many functions including transport, cell signaling, and anchoring the cytoskeleton. Together, the components of the membrane give it key properties such as selective permeability and fluidity to control what enters and exits the cell while protecting it.
The document summarizes the endomembrane system and Golgi apparatus. It describes the Golgi apparatus as a smooth membrane-bound organelle found in eukaryotic cells that is involved in secretion and processing of proteins and lipids. It discusses the discovery of the Golgi apparatus, its ultrastructure consisting of stacked cisternae and vesicles, its functions in secretion, glycosylation, and formation of other organelles. The summary concludes by stating that the Golgi apparatus is an essential membrane organelle in the secretory pathway of eukaryotic cells.
This document summarizes key points about cell membranes and cellular transport from Chapter 5 of a biology textbook. It discusses how membranes are composed of phospholipids and proteins arranged in a fluid mosaic structure. It describes different types of passive transport including diffusion, facilitated diffusion, and osmosis. Active transport requires energy in the form of ATP to move molecules against their concentration gradient. Large molecules are transported across membranes via exocytosis and endocytosis. The chapter emphasizes that ATP acts as the cell's energy currency, powering various types of cellular work through energy coupling reactions.
The document summarizes key concepts about membrane structure and function from a biology textbook chapter. It discusses how the plasma membrane is a fluid mosaic of lipids and proteins that forms a selectively permeable barrier. Membrane proteins and transport proteins allow certain substances to pass through the membrane via passive transport processes like diffusion and osmosis, maintaining water balance in cells.
The plasma membrane is selectively permeable and allows some substances to pass through more easily than others. It contains phospholipids arranged in a bilayer with hydrophobic tails interacting in the middle and hydrophilic heads facing outwards. Embedded proteins can be integral and span the entire membrane or peripheral and attach to surface. The fluid mosaic model describes the membrane as a fluid structure with phospholipids and proteins able to move laterally. Transport across the membrane can be passive via diffusion, osmosis, and facilitated diffusion or active via protein pumps and requires cell energy. Endocytosis and exocytosis involve vesicle transport across the membrane.
The document summarizes the structure and function of microtubules in eukaryotic cells. It discusses how microtubules are composed of protein subunits that assemble into hollow tubes. Microtubules emanate from microtubule organizing centers and serve important roles as structural supports, in intracellular transport through motor proteins like kinesin and dynein, and in cell division through formation of the mitotic spindle. Microtubules are also the main components of cilia and flagella and enable their bending movements through the motor protein dynein.
The document discusses the key components of the cytoskeleton - microtubules, microfilaments, and intermediate filaments - and how they work together to maintain cell shape, allow movement of organelles and vesicles, transport materials within the cell, and enable cell movement through polymerization and interaction with motor proteins like myosin and kinesin. The cytoskeleton is a dynamic network that forms various structures through accessory proteins and allows rapid changes in cell morphology.
Cilia and flagella are organelles found in eukaryotic cells that are used for cellular transportation. Cilia are short and numerous, while flagella are longer and fewer in number. Both are composed of microtubules in a 9+2 pattern and use dynein arms powered by ATP to bend back and forth, propelling the cell. Cilia movement is coordinated to move cells in waves, while flagella rotation provides smoother movement. Defects can impact functions like respiration and kidney function.
The document provides an overview of metabolism and energy transformations in cells. It discusses how (1) cells extract and use energy to perform work through thousands of chemical reactions organized into metabolic pathways, (2) the laws of thermodynamics govern energy transformations with energy being conserved but entropy increasing, and (3) ATP powers cellular work by coupling exergonic reactions like its hydrolysis to endergonic reactions like transport or synthesis through energy transfer.
This document provides an overview of Chapter 7 from Campbell Biology, Ninth Edition. It discusses membrane structure and function, including the fluid mosaic model of membranes and the roles of lipids and proteins. Key points covered include the selective permeability of the plasma membrane, the fluidity of membranes, membrane protein functions like transport and signaling, and the role of carbohydrates in cell-cell recognition.
The document summarizes key concepts about membrane structure and function from Chapter 7 of Campbell Biology. It discusses the fluid mosaic model of membrane structure, which states that membranes are made of a phospholipid bilayer with various proteins embedded within. Membranes are selectively permeable, allowing some substances to pass through via passive transport mechanisms like diffusion and facilitated diffusion. Membranes regulate the movement of substances in and out of cells.
Describes the plasma membrane in detail, explains the each major component with its functions.
Transport mechanism across the cell is covered with detailed explanation with examples.
by Dr. N.Sivaranjani, MD
The endoplasmic reticulum (ER) is an organelle found in eukaryotic cells that forms an interconnected network of tubules, vesicles, and cisternae. It has two main types - rough ER with ribosomes and smooth ER without. The rough ER is involved in protein synthesis and modification, while the smooth ER performs functions like lipid synthesis and calcium regulation. Newly synthesized proteins are transported from the ER to the Golgi apparatus in vesicles for further processing and modification before being packaged into secretory vesicles and transported throughout the cell. The ER also plays a key role in protein folding and quality control.
The endoplasmic reticulum is a network of folded membranes found throughout the cytoplasm of eukaryotic cells. It was first observed in 1945 by Albert Claude using an electron microscope. The endoplasmic reticulum is divided into two subcompartments: the rough endoplasmic reticulum, which is studded with ribosomes, and the smooth endoplasmic reticulum, which lacks ribosomes. The rough endoplasmic reticulum is the site of protein synthesis and transports proteins throughout the cell, while the smooth endoplasmic reticulum is involved in lipid and steroid metabolism.
Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, water and carbon dioxide to produce oxygen and energy in the form of glucose. It occurs in chloroplasts and involves two stages - the light-dependent reactions where ATP and NADPH are produced, and the light-independent Calvin cycle where glucose is formed. Chlorophyll and other pigments absorb sunlight which is used to power the transfer of electrons and production of chemical energy carriers. Photosynthesis ultimately feeds the biosphere by producing organic molecules and oxygen from inorganic sources.
Cell junctions are multiprotein complexes that provide contact between adjacent animal cells and help hold tissues together. The main types are anchoring junctions, which attach cells to surrounding matrix and each other; gap junctions, which allow direct communication between cells; and tight junctions, which form barriers between epithelial layers. Cell junction molecules like selectins, cadherins, integrins, and the immunoglobulin superfamily mediate cell-cell adhesion through calcium-dependent and calcium-independent binding of domains on neighboring cell surfaces. Cell junctions are essential for tissue structure, cell signaling, and barrier functions in the body.
KEY CONCEPTS
6.1 Biologists use microscopes and the tools of biochemistry to
study cells
6.2 Eukaryotic cells have internal membranes that
compartmentalize their functions
6.3 The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes
6.4 The endomembrane system regulates protein traffic and
performs metabolic functions in the cell
6.5 Mitochondria and chloroplasts change energy from one form to another
6.6 The cytoskeleton is a network of fibers that organizes structures and activities in the cell
6.7 Extracellular components and connections between cells help coordinate cellular activities
This document discusses lysosomes and chaperone-mediated autophagy (CMA). It provides background on the discovery of lysosomes and their structure and functions. Lysosomes contain hydrolytic enzymes and digest macromolecules, cellular debris, and foreign material. CMA selectively degrades cytosolic proteins through binding to a chaperone and lysosomal membrane protein LAMP-2A. Disruption of CMA is implicated in diseases like Parkinson's and cancer. CMA activity declines with age.
A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle.
More than half of all proteins interact with membranes.
The cytoskeleton is a network of protein filaments and tubules that gives cells their shape and allows them to move. It has three main components: microtubules, microfilaments, and intermediate filaments. Microtubules are hollow tubes involved in intracellular transport and cell division. Microfilaments made of actin help with cell movement and shape. Intermediate filaments provide structural support. Together, the cytoskeleton transports vesicles, separates chromosomes, allows muscle contraction, and maintains cell shape.
Biological membranes are thin, flexible surfaces that separate cells and organelles from their environments. They are made up of proteins, lipids like phospholipids and glycolipids, and carbohydrates. Phospholipids are the major lipid component, consisting of a hydrophilic head and two hydrophobic tails, allowing them to form the fluid lipid bilayer structure of the membrane. Membrane proteins can be integral and span the membrane or peripheral and attach to its surface. They perform many functions including transport, cell signaling, and anchoring the cytoskeleton. Together, the components of the membrane give it key properties such as selective permeability and fluidity to control what enters and exits the cell while protecting it.
The document summarizes the endomembrane system and Golgi apparatus. It describes the Golgi apparatus as a smooth membrane-bound organelle found in eukaryotic cells that is involved in secretion and processing of proteins and lipids. It discusses the discovery of the Golgi apparatus, its ultrastructure consisting of stacked cisternae and vesicles, its functions in secretion, glycosylation, and formation of other organelles. The summary concludes by stating that the Golgi apparatus is an essential membrane organelle in the secretory pathway of eukaryotic cells.
This document summarizes key points about cell membranes and cellular transport from Chapter 5 of a biology textbook. It discusses how membranes are composed of phospholipids and proteins arranged in a fluid mosaic structure. It describes different types of passive transport including diffusion, facilitated diffusion, and osmosis. Active transport requires energy in the form of ATP to move molecules against their concentration gradient. Large molecules are transported across membranes via exocytosis and endocytosis. The chapter emphasizes that ATP acts as the cell's energy currency, powering various types of cellular work through energy coupling reactions.
The document summarizes key concepts about membrane structure and function from a biology textbook chapter. It discusses how the plasma membrane is a fluid mosaic of lipids and proteins that forms a selectively permeable barrier. Membrane proteins and transport proteins allow certain substances to pass through the membrane via passive transport processes like diffusion and osmosis, maintaining water balance in cells.
1) Membranes are composed of a bilayer of phospholipids with embedded and attached proteins. Membrane proteins perform many functions including cell shape maintenance, signaling, transport, and more.
2) Passive transport is diffusion across membranes without energy expenditure. Osmosis is the diffusion of water across selectively permeable membranes down its concentration gradient.
3) Enzymes lower the activation energy of chemical reactions, increasing the reaction rate without being consumed. Each enzyme is highly specific to its substrate due to the shape of its active site.
The document provides an overview of cellular membranes and membrane transport. It discusses how membranes are fluid mosaics composed of phospholipids and proteins that allow selective permeability. Membranes regulate transport across cellular boundaries through passive diffusion down concentration gradients and facilitated transport using channel and carrier proteins. The plasma membrane separates the cell from its surroundings and exhibits selective permeability through these transport mechanisms.
The document provides an overview of cellular membranes and membrane transport. It discusses how membranes are fluid mosaics composed of phospholipids and proteins that allow selective permeability. Membranes regulate transport across cellular boundaries through passive diffusion down concentration gradients and facilitated transport using channel and carrier proteins. The plasma membrane separates the cell from its surroundings and exhibits selective permeability through these transport mechanisms.
This document provides an overview of membrane structure and function from Campbell Biology 10th Edition. It discusses how membranes are composed of a phospholipid bilayer with various integral and peripheral proteins embedded. Membranes exhibit selective permeability due to their structure, allowing some substances to pass through more easily via diffusion or transport proteins. Membrane proteins perform important functions like transport, signaling, and cell recognition. Membrane structure results in passive transport down concentration gradients without cellular energy input.
The document discusses membrane structure and function. It describes the fluid mosaic model of the plasma membrane, which depicts a bilayer of phospholipids with embedded and peripheral proteins. Membrane proteins allow the membrane to facilitate various transport mechanisms like passive diffusion, facilitated diffusion, and active transport via pumps and channels. Transport proteins move molecules across membranes through simple diffusion, facilitated diffusion using carrier proteins, osmosis, and active transport requiring ATP. Vesicles and bulk flow processes like endocytosis and exocytosis are also used to transport larger particles across the membrane.
The document provides an overview of membrane structure and function:
1. It describes the fluid mosaic model of the plasma membrane, which explains that membranes are composed of a bilayer of phospholipids embedded with integral and peripheral proteins that give the membrane a fluid structure.
2. The key components of cell membranes are phospholipids, cholesterol, and integral and peripheral proteins. Transport proteins like channel and carrier proteins allow selective permeability across the membrane.
3. Membrane proteins have a variety of important roles including cell-cell recognition, transport, enzymatic activity, and attachment to intracellular structures. The fluid mosaic structure and selective permeability of membranes allows them to regulate cellular traffic.
The document discusses membrane structure and function. It covers topics such as the fluid mosaic model of membranes, membrane components like phospholipids and proteins, membrane fluidity, transport mechanisms like passive diffusion and active transport, and bulk transport processes like exocytosis. The key points are that cellular membranes are fluid mosaics of lipids and proteins, transport can be passive or active, and large molecules cross membranes in bulk through exocytosis and endocytosis.
The document summarizes key concepts about cell membranes:
1. Cell membranes are made of a phospholipid bilayer with integral and peripheral proteins embedded. Cholesterol adds structure and prevents extremes of fluidity.
2. Membrane proteins perform important functions like transport, signaling, and attachment to the cytoskeleton.
3. Passive transport like diffusion and facilitated diffusion moves molecules down concentration gradients without energy. Active transport uses protein pumps and ATP to move molecules against gradients.
The document discusses the structure and functions of the plasma membrane. It describes the plasma membrane as a fluid mosaic of phospholipids and membrane proteins. Key points include:
- The plasma membrane is a lipid bilayer composed of phospholipids and cholesterol that encloses the cell.
- The fluid mosaic model describes the membrane as a fluid structure with integral and peripheral proteins embedded within the phospholipid bilayer.
- Membrane proteins perform important functions like transport, signaling, and cell recognition. Transport proteins include channel and carrier proteins.
- The plasma membrane regulates what enters and exits the cell and plays a critical role in cell function. Dysfunctions can lead to diseases.
The document summarizes key aspects of cell structure and function. It describes that eukaryotic cells have internal membranes that compartmentalize functions, while prokaryotic cells do not. The main organelles of eukaryotic cells are then outlined, including the nucleus, endomembrane system, mitochondria and chloroplasts, cytoskeleton, and extracellular connections between cells.
The cell membrane has a fluid mosaic structure consisting of a phospholipid bilayer with embedded proteins. The phospholipid bilayer forms two layers with hydrophobic fatty acid tails in the middle and hydrophilic phosphate heads on the outside contacting water. Some proteins are embedded in the membrane while others are peripherally attached. This structure allows the membrane to be selectively permeable and control what enters and exits the cell through transport proteins and pores.
Cells require transport mechanisms to move substances into and out of them. There are different mechanisms including diffusion, osmosis, and active transport. The cell membrane is a selectively permeable barrier composed of a phospholipid bilayer and embedded proteins. Transport proteins such as carrier and channel proteins facilitate the passage of molecules across the membrane through diffusion or active transport powered by ATP.
in this notes we will study and learn about
cell membrane
parts of cell membrane
different formation of cell membrane
lipids present in cell membrane
function of cell membrane
The plasma membrane is composed of a phospholipid bilayer with proteins embedded within it. Singer and Nicolson proposed the fluid mosaic model which states that the membrane is a fluid structure with phospholipids able to move laterally within the bilayer and transmembrane proteins dispersed throughout. Key aspects of the model are that membranes are fluid and dynamic, allowing for selective permeability and various protein functions such as transport and signaling.
The document discusses cell differentiation and specialized cell functions. It states that the human body contains about 200 different cell types that are all derived from a single fertilized egg cell. During cell differentiation, cells undergo specialization where they synthesize specific proteins, change shape, and become efficient at specialized functions. For example, muscle cells elongate and accumulate actin and myosin, specializing in force generation. The document then discusses some main cellular functions performed by specialized cells and provides examples of membrane structure and organization in cells.
The plasma membrane maintains the internal environment of cells by regulating what enters and exits. It is composed primarily of a phospholipid bilayer with embedded protein molecules and cholesterol. The membrane is selectively permeable and uses both passive and active transport mechanisms to control molecular movement in and out of cells.
The document discusses the structure and functions of plasma membranes. It begins by describing the plasma membrane as a selectively permeable barrier that separates the cell from its surroundings. The membrane is made up of a fluid mosaic of phospholipids and proteins. Phospholipids form a lipid bilayer with hydrophilic heads and hydrophobic tails. Membrane proteins are embedded within the bilayer. The membrane is fluid and allows for lateral movement of components. Membranes regulate the passage of substances through passive diffusion, facilitated diffusion using transport proteins, and active transport using ATP-powered pumps. Membranes also contain integral and peripheral proteins that carry out important cell functions like transport, signaling, recognition and attachment.
This document provides an overview of Chapter 5 from Campbell Biology: Concepts & Connections. It discusses several key topics:
1. Membrane structure and function, including the fluid mosaic model and roles of membrane proteins like transporters and receptors.
2. Passive transport mechanisms like diffusion and osmosis that move molecules across membranes down concentration gradients without energy expenditure.
3. Active transport which requires energy (ATP) to move molecules against concentration gradients using transport proteins.
4. Endocytosis and exocytosis which transport large molecules across membranes within vesicles that fuse with the membrane.
The document discusses chemical bonding and how carbon can exist in different forms like charcoal, coal, and soot. When soot is subjected to high temperature and pressure, it can form diamond. This process of changing forms can be explained by understanding the chemical bonds between atoms - specifically how the bonds hold atoms together in each structure.
The document outlines learning objectives that cover topics including the electrical properties of atoms, experiments that led to the discovery of X-rays and radioactivity, distinguishing between alpha, beta and gamma radiation, describing the nuclear model of the atom and its parts, writing electron configurations, and explaining how splitting and combining of hydrogen and oxygen relates to energy. The objectives will help students explain atomic structure and properties using concepts from electricity, nuclear physics, and quantum mechanics.
This document provides learning objectives and content about atomic theory and the development of the periodic table. It discusses the following key points:
- The ancient Greek ideas about matter being made of four elements.
- Important laws like the Law of Conservation of Mass and the Law of Definite Proportions.
- How atomic theory developed from the Greek idea of atoms to Dalton's atomic theory to explain these laws.
- How elements are arranged in the periodic table based on their properties and why this arrangement is significant.
- The distinction between atoms and molecules and identification of hazardous or rare elements.
- How green chemistry aims to reduce reliance on hazardous elements.
This chapter introduces key concepts in chemistry including distinguishing science from technology, defining important terms like hypothesis and theory, and classifying types of matter. It outlines learning objectives related to the states and properties of matter, physical and chemical changes, and using units and calculations. Students will learn to differentiate elements, compounds, mixtures and various research types as well as manipulate matter concepts like density, heat, temperature and phases. Critical thinking skills will also be developed.
The document discusses several key concepts regarding genetics:
1) It compares purebred and mutt dogs, noting that purebreds experience less genetic variation due to selective breeding while mutts have more variation.
2) It discusses Gregor Mendel's experiments with pea plants which formed the basis of modern genetics and led to his laws of inheritance.
3) It explains Mendel's laws of segregation and independent assortment, how alleles segregate and assort independently during gamete formation and fertilization.
4) It discusses how many traits are influenced not just by genetics but also the environment, and that inheritance follows probabilistic rules.
The document discusses various biological processes related to digestion, transport, and excretion. It includes topics like the levels of biological organization, different modes of nutrient acquisition like suspension feeding and substrate feeding, and membrane transport mechanisms like diffusion, osmosis, and aquaporins. It also covers organ system functions, comparing the digestive and excretory systems of carnivores and herbivores, as well as osmoregulation in fish and mammals.
1. Frederick Banting and Charles Best discovered insulin in the 1920s while experimenting with pancreatic extracts from dogs at the University of Toronto.
2. Their early experiments showed that extracts from the pancreatic islets of Langerhans could lower blood sugar levels in diabetic dogs.
3. The first successful use of insulin on a human, a 14-year-old boy dying of diabetes, helped establish insulin as an effective treatment for diabetes. Banting and Best were later awarded the Nobel Prize for their discovery.
Most of the world's population is lactose intolerant because they lack the enzyme lactase as adults. There are different types of lactose intolerance, including primary lactase deficiency which is genetic and affects adults, secondary deficiency caused by intestinal injury, and congenital deficiency present from birth. Lactose intolerance is caused by a lactase deficiency rather than an immune response like milk allergy.
1) Photosynthesis and cellular respiration are interdependent processes that provide energy for life on Earth. Photosynthesis uses energy from sunlight to produce glucose from carbon dioxide and water, releasing oxygen. Cellular respiration uses oxygen and glucose to produce carbon dioxide, water, and ATP, the energy currency of cells.
2) Cellular respiration occurs in three stages - glycolysis, the citric acid cycle, and oxidative phosphorylation. Glycolysis breaks down glucose, the citric acid cycle generates electron carriers, and oxidative phosphorylation uses an electron transport chain to produce ATP through chemiosmosis.
3) Fermentation allows cells to produce ATP without oxygen through pathways like lactic acid fermentation and alcohol fermentation. It takes advantage
This document provides a summary of key concepts relating to communities, ecosystems, and their structure and function. It discusses topics like biotic interactions between species, characteristics of communities, trophic structure and energy flow through ecosystems, and human impacts and disturbances to communities and nutrient cycles. Specific examples are given to illustrate concepts like symbiotic relationships, keystone species, mimicry, and how altered ecosystems can disrupt nutrient cycling.
1. Photosynthesis is the process by which plants use sunlight, carbon dioxide, and water to produce oxygen and energy in the form of sugar.
2. It takes place in chloroplasts, which contain chlorophyll and other pigments to absorb sunlight and drive a series of chemical reactions.
3. Photosynthesis has two stages: the light reactions where sunlight is absorbed and used to produce ATP and NADPH, and the dark reactions where carbon dioxide is fixed into sugars using ATP and NADPH produced in the light reactions.
This document discusses several topics related to ecology and population biology, including:
1) It introduces the concepts of r-selected and K-selected species, which have different life history strategies related to population stability and resource availability.
2) It discusses different types of population growth patterns (exponential, logistic) and factors (density-dependent, density-independent) that influence population growth rates.
3) It provides examples of applying mathematical models to analyze population growth and examines survivorship curves and life tables used to study reproduction and mortality among species.
Ch 34: The Biosphere & Earth's Environmentsn_bean1973
The document discusses a milky green cloud seen off the coast of Namibia in southern Africa. This cloud is caused by hydrogen sulfide gas rising from the ocean floor, which is produced by anaerobic bacteria breaking down organic matter. As the gas reaches the surface and interacts with oxygen, it forms pure sulfur that appears white or yellowish and tints the water milky green. These periodic occurrences can cause die-offs of fish populations for the local fishing industry.
The document contains figures and explanations related to chemistry concepts such as the formation of ionic and covalent bonds between atoms. Figure 2-7a shows the transfer of an electron from a sodium atom to a chlorine atom, forming sodium and chloride ions and the ionic compound sodium chloride. Figure 2-13a illustrates that hydrogen bonds between water molecules are constantly breaking and reforming in liquid water but are stable in ice.
This document contains numerous labeled figures that outline biological concepts from the smallest to largest levels of organization, including: atoms and molecules that make up DNA; cells; tissues, organs and organ systems; organisms; populations and communities; ecosystems; and domains and kingdoms of life. It also includes figures illustrating scientific concepts like natural selection and evolution, as well as the scientific method through an example of testing hypotheses.
How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
Executive Directors Chat Leveraging AI for Diversity, Equity, and InclusionTechSoup
Let’s explore the intersection of technology and equity in the final session of our DEI series. Discover how AI tools, like ChatGPT, can be used to support and enhance your nonprofit's DEI initiatives. Participants will gain insights into practical AI applications and get tips for leveraging technology to advance their DEI goals.
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
Main Java[All of the Base Concepts}.docxadhitya5119
This is part 1 of my Java Learning Journey. This Contains Custom methods, classes, constructors, packages, multithreading , try- catch block, finally block and more.
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
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The simplified electron and muon model, Oscillating Spacetime: The Foundation...RitikBhardwaj56
Discover the Simplified Electron and Muon Model: A New Wave-Based Approach to Understanding Particles delves into a groundbreaking theory that presents electrons and muons as rotating soliton waves within oscillating spacetime. Geared towards students, researchers, and science buffs, this book breaks down complex ideas into simple explanations. It covers topics such as electron waves, temporal dynamics, and the implications of this model on particle physics. With clear illustrations and easy-to-follow explanations, readers will gain a new outlook on the universe's fundamental nature.
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26. Selectively permeable membrane Solute molecule Lower concentration of solute H 2 O Solute molecule with cluster of water molecules Net flow of water Water molecule Equal concentration of solute Higher concentration of solute
45. Coated vesicle Coated pit Specific molecule Receptor-mediated endocytosis Coat protein Receptor Coated pit Material bound to receptor proteins Plasma membrane
46.
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56. Fuel Gasoline Energy conversion in a cell Energy for cellular work Cellular respiration Waste products Energy conversion Combustion Energy conversion in a car Oxygen Heat Glucose Oxygen Water Carbon dioxide Water Carbon dioxide Kinetic energy of movement Heat energy
57. Fuel Gasoline Waste products Energy conversion Combustion Energy conversion in a car Oxygen Water Carbon dioxide Kinetic energy of movement Heat energy
58. Energy conversion in a cell Energy for cellular work Cellular respiration Heat Glucose Oxygen Water Carbon dioxide Fuel Energy conversion Waste products
59.
60. Reactants Amount of energy released Potential energy of molecules Energy released Products
69. Chemical work Solute transported Molecule formed Product Reactants Motor protein Membrane protein Solute Transport work Mechanical work Protein moved
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71. Energy from exergonic reactions Energy for endergonic reactions Phosphorylation Hydrolysis
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75. Reaction without enzyme E A with enzyme Energy Reactants Reaction with enzyme E A without enzyme Net change in energy (the same) Products Progress of the reaction
78. Enzyme available with empty active site Active site 1 Enzyme (sucrase) Substrate binds to enzyme with induced fit 2 Substrate (sucrose)
79. Enzyme available with empty active site Active site 1 Enzyme (sucrase) Substrate binds to enzyme with induced fit 2 Substrate (sucrose) Substrate is converted to products 3
80. Enzyme available with empty active site Active site 1 Enzyme (sucrase) Substrate binds to enzyme with induced fit 2 Substrate (sucrose) Substrate is converted to products 3 Products are released 4 Fructose Glucose
81.
82.
83.
84. Substrate Enzyme Active site Normal binding of substrate Competitive inhibitor Enzyme inhibition Noncompetitive inhibitor
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87. Diffusion Requires no energy Passive transport Higher solute concentration Facilitated diffusion Osmosis Higher water concentration Higher solute concentration Requires energy Active transport Solute Water Lower solute concentration Lower water concentration Lower solute concentration
88. ATP cycle Energy from exergonic reactions Energy for endergonic reactions
89. Molecules cross cell membranes passive transport by by may be moving down moving against requires uses diffusion of polar molecules and ions uses of (a) (c) (d) (b) (e)
This chapter describes how working cells, such as those found in a prey organism, use cellular metabolism directed by enzymes associated with membranes to convert energy.
The structure of the membrane is described as a fluid mosaic model . Scientists propose models as hypotheses, which are ways of explaining existing information. Sometimes models are replaced with an updated version. Models inspire experiments, and few models survive these tests without modifications. The fluid mosaic model is being continually refined. You may want to mention to your students that because of the hydrophobic properties of the tail of phospholipids, lipid bilayers are naturally self-healing. Teaching Tips 1. You might wish to share a very simple analogy that seems to work well for some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy by finding exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
Campbell, Neil, and Jane Reece, Biology , 8th ed., Figure 7.3 The fluid mosaic model for membranes.
The bilayer is about as fluid as salad or cooking oil. Teaching Tips 1. You might wish to share a very simple analogy that seems to work well for some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy by finding exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
Campbell, Neil, and Jane Reece, Biology , 8th ed., Figure 7.2 Phospholipid bilayer (cross section).
Teaching Tips 1. You might wish to share a very simple analogy that seems to work well for some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy by finding exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
Figure 5.1A The plasma membrane and extracellular matrix of an animal cell.
Carbohydrates vary among individual cells and function as markers. For example, the four human blood types designated A, B, AB, and O reflect variation in the carbohydrates on the surface of red blood cells. Teaching Tips 1. You might wish to share a very simple analogy that seems to work well for some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy by finding exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
Membrane proteins called transport proteins play a “gatekeeper” role in selective permeability. Teaching Tips 1. You might wish to share a very simple analogy that seems to work well for some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy by finding exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.)
Figure 5.1B Enzyme activity.
Figure 5.1C Signal transduction.
Figure 5.1D Transport.
All cell membranes are similar in structure and function. This is a excellent point to illustrate the evolutionary unity of life. Teaching Tips 1. The hydrophobic and hydrophilic ends of a phospholipid molecule create a lipid bilayer. The hydrophobic edges of the layer will also seal to other such edges, eventually wrapping a sheet into a sphere that can enclose water (a simple cell—see Module 4.5). Furthermore, because of these hydrophobic properties, lipid bilayers are naturally self-healing. All of these properties emerge from the structure of phospholipids.
Figure 5.2 Artificial membrane-bound sacs.
Figure 5.2 Diagram of a section of a membrane sac.
Much of the traffic across a membrane occurs by diffusion down its concentration gradient. This is exemplified by the diffusion of oxygen across the plasma membrane of a cell actively utilizing oxygen. As long as the cell is using the oxygen, the concentration from outside to inside will be maintained. For the BLAST Animation Diffusion, go to Animation and Video Files. Student Misconceptions and Concerns 1. For students with limited science backgrounds, concepts such as diffusion and osmosis can take considerable time to fully understand and apply. Instructors often struggle to remember a time in their lives when they did not know about such fundamental scientific principles. Consider spending extra time to illustrate and demonstrate these key processes to the class. Consider short interactive class exercises in which students create analogies or think of examples of these principles in their lives. Teaching Tips 1. Students often benefit from reminders of diffusion in their lives. Smells can usually be traced back to their sources—the smell of dinner on the stove, the scent of perfume or cologne from a bottle, the smoke drifting away from a campfire. These scents are strongest nearest the source and weaker as we move away. 2. Consider demonstrating simple diffusion. A large jar of water and a few drops of ark-colored dye work well over the course of a lecture period. Alternatively, release a strong scent of cologne or peppermint or peel part of an orange in the classroom and have students raise their hands as they first detect the smell. Students nearest the source will raise their hands before students farther away. The fan from an active overhead projector or overhead vent may bias the experiment a bit, so be aware of any directed movements of air in your classroom that might disrupt this demonstration.
Because membranes are selectively permeable, they have different effects on the rates of diffusion of various molecules. For the BLAST Animation Passive Diffusion Across a Membrane, go to Animation and Video Files. Student Misconceptions and Concerns 1. For students with limited science backgrounds, concepts such as diffusion and osmosis can take considerable time to fully understand and apply. Instructors often struggle to remember a time in their lives when they did not know about such fundamental scientific principles. Consider spending extra time to illustrate and demonstrate these key processes to the class. Consider short interactive class exercises in which students create analogies or think of examples of these principles in their lives. Teaching Tips 1. Students often benefit from reminders of diffusion in their lives. Smells can usually be traced back to their sources—the smell of dinner on the stove, the scent of perfume or cologne from a bottle, the smoke drifting away from a campfire. These scents are strongest nearest the source and weaker as we move away. 2. Consider demonstrating simple diffusion. A large jar of water and a few drops of dark-colored dye work well over the course of a lecture period. Alternatively, release a strong scent of cologne or peppermint or peel part of an orange in the classroom and have students raise their hands as they first detect the smell. Students nearest the source will raise their hands before students farther away. The fan from an active overhead projector or overhead vent may bias the experiment a bit, so be aware of any directed movements of air in your classroom that might disrupt this demonstration.
Figure 5.3A Passive transport of one type of molecule.
Figure 5.3B Passive transport of two types of molecules.
Student Misconceptions and Concerns 1. For students with limited science backgrounds, concepts such as diffusion and osmosis can take considerable time to fully understand and apply. Instructors often struggle to remember a time in their lives when they did not know about such fundamental scientific principles. Consider spending extra time to illustrate and demonstrate these key processes to the class. Consider short interactive class exercises in which students create analogies or think of examples of these principles in their lives. Teaching Tips 1. Your students may have noticed that the skin of their fingers wrinkles after taking a long shower or bath, or after washing dishes. The skin wrinkles because it is swollen with water but still tacked down at some points. Through osmosis, water moves into the epidermal skin cells. Our skin is hypertonic to these solutions, producing the swelling that appears as large wrinkles. Oils inhibit the movement of water into our skin. Thus, soapy water results in wrinkling faster than plain water because the soap removes the natural layer of oil from our skin.
Figure 5.4 Osmosis, the diffusion of water across a membrane. Note that osmosis is a force that is actually able to cause a differential in water levels in the two arms of the U-tube shown in Figure 5.4.
Seawater is isotonic to many marine invertebrates. The cells of most terrestrial animals are bathed in an extracellular fluid that is isotonic to their cells. If cells are put into a hypotonic or hypertonic solution, the results can be dangerous for the cell. Your students may have noticed that the skin of their fingers wrinkles after taking a long shower or bath or washing dishes. The skin wrinkles because it is swollen with water but still tacked down at some points. By osmosis, water moves into the epidermal skin cells. Our skin is hypertonic to these solutions, producing the swelling that appears as large wrinkles. Student Misconceptions and Concerns 1. Students easily confuse the term hypertonic and hypotonic. One challenge is to get them to understand that these are relative terms, like heavier, darker, or fewer. No single object is heavier, no single cup of coffee is darker, and no single bag of M & M’s has fewer candies. Such terms only apply when comparing two or more items. A solution with a higher concentration than another solution is hypertonic to that solution. However, the same solution might also be hypotonic to a third solution. Teaching Tips 1. The word root hypo- means “below.” Thus, a hypodermic needle injects substances below the dermis. Students might best remember that hypotonic solutions have concentrations of solutes below that of the other solution(s). 2. After introducing the idea of hypertonic and hypotonic solutions, you may wish to challenge your students with the following: A marine salmon moves from the ocean up a freshwater stream to reproduce. The salmon is moving from a _____ environment to a _____ environment. (Answers: hypertonic, hypotonic) 3. The effects of hypertonic and hypotonic solutions can be demonstrated if students soak carrot sticks, long slices of potato, or celery in hypertonic and hypotonic solutions. These also make nice class demonstrations.
Organisms with cell walls are protected from lysis when exposed to a hypotonic environment. Student Misconceptions and Concerns 1. Students easily confuse the term hypertonic and hypotonic. One challenge is to get them to understand that these are relative terms, like heavier, darker, or fewer. No single object is heavier, no single cup of coffee is darker, and no single bag of M & M’s has fewer candies. Such terms only apply when comparing two or more items. A solution with a higher concentration than another solution is hypertonic to that solution. However, the same solution might also be hypotonic to a third solution. Teaching Tips 1. The word root hypo- means “below.” Thus, a hypodermic needle injects substances below the dermis. Students might best remember that hypotonic solutions have concentrations of solutes below that of the other solution(s). 2. After introducing the idea of hypertonic and hypotonic solutions, you may wish to challenge your students with the following: A marine salmon moves from the ocean up a freshwater stream to reproduce. The salmon is moving from a _____ environment to a _____ environment. (Answers: hypertonic, hypotonic) 3. The effects of hypertonic and hypotonic solutions can be demonstrated if students soak carrot sticks, long slices of potato, or celery in hypertonic and hypotonic solutions. These also make nice class demonstrations.
Figure 5.5 How animal and plant cells behave in different solutions.
Polar molecules and ions that are impeded by the lipid bilayer diffuse with the help of transport proteins. Teaching Tips 1. The text notes that “the greater the number of transport proteins for a particular solute present in a membrane, the faster the solute’s rate of diffusion across the membrane.” This is similar to a situation that might be more familiar to your students. The more ticket-takers present at the entrance to a stadium, the faster the rate of movement of people into the stadium.
Aquaporins, the water-channel proteins, facilitate the massive amount of diffusion that occurs in plant cells and red blood cells. Teaching Tips 1. The text notes that “the greater the number of transport proteins for a particular solute present in a membrane, the faster the solute’s rate of diffusion across the membrane.” This is similar to a situation that might be more familiar to your students. The more ticket-takers present at the entrance to a stadium, the faster the rate of movement of people into the stadium.
Figure 5.6 Transport protein providing a channel for the diffusion of a specific solute across a membrane.
Kidney problems can result from defective kidney cells that have defective aquaporin molecules. Teaching Tips 1. The functional significance of aquaporins in cell membranes is somewhat like open windows in a home. Even without windows, air moves slowly into and out of a home. Open windows and aquaporins facilitate the process of these movements, speeding them up.
Figure 5.7 Peter Agre.
The importance of these transport proteins is their ability to move solutes from a low concentration to a high concentration. ATP energy is required. The sodium-potassium pump that helps maintain gradients shuttles sodium and potassium across the membrane against their concentration gradients. The generation of nerve signals also depends on concentration differences. For the BLAST Animation Active Transport, go to Animation and Video Files. Teaching Tips 1. Active transport uses energy to move a solute against its concentration gradient. Challenge your students to think of the many possible analogies to this situation, for example, bailing out a leaky boat by moving water back to a place (outside the boat) where water is more concentrated. An alternative analogy might be the herding of animals, which requires work to keep the organisms concentrated and counteract their natural tendency to spread out. 2. Students familiar with city subway toll stations might think of some gate mechanisms that work similarly to the proteins regulating active transport. A person steps up to a barrier and inserts payment (analogous to ATP input), and the gate changes shape, permitting passage to the other side. Even a simple turnstile system that requires payment is generally similar.
Figure 5.8 Active transport of a solute across a membrane.
Figure 5.8 Active transport of a solute across a membrane.
Figure 5.8 Active transport of a solute across a membrane.
Figure 5.8 Active transport of a solute across a membrane.
When the vesicles fuse with the cell membrane, the vesicle becomes part of the membrane. An example of exocytosis is the excretion of insulin by cells within the pancreas. Teaching Tips 1. Students carefully considering exocytosis might notice that membrane from secretory vesicles is added to the plasma membrane. Consider challenging your students to identify mechanisms that balance out this enlargement of the cell surface. (Endocytosis “subtracts” area from the cell surface. It is a major factor balancing out the additional membrane supplied by exocytosis.)
These mechanisms occur continually in most eukaryotic cells with the amount of plasma membrane remaining constant in a nongrowing cell. Apparently, the addition of membrane by one process offsets the loss of membrane by the other. For the BLAST Animation Endocytosis and Exocytosis, go to Animation and Video Files. Teaching Tips Students carefully considering exocytosis might notice that membrane from secretory vesicles is added to the plasma membrane. Consider challenging your students to identify mechanisms that balance out this enlargement of the cell surface. (Endocytosis “subtracts” area from the cell surface. It is a major factor balancing out the additional membrane supplied by exocytosis.)
Figure 5.9 Three kinds of endocytosis.
Figure 5.9 Three kinds of endocytosis.
Figure 5.9 Three kinds of endocytosis.
Figure 5.9 Three kinds of endocytosis.
Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. Teaching Tips 1. In our daily lives, we rely upon many energy transformations. On our classroom walls, a clock converts electrical energy to mechanical energy to sweep the hands around the clock’s face. Our physical (mechanical) activities walking to and from the classroom rely upon the chemical energy from our diet. This chemical energy in our diet also helps us maintain a steady body temperature (heat). Consider challenging your students to come up with additional examples of such common energy conversions.
Energy is fundamental to all metabolic processes. Bioenergetics is the study of how energy flows through living organisms. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. Teaching Tips 1. In our daily lives, we rely upon many energy transformations. On our classroom walls, a clock converts electrical energy to mechanical energy to sweep the hands around the clock’s face. Our physical (mechanical) activities walking to and from the classroom rely upon the chemical energy from our diet. This chemical energy in our diet also helps us maintain a steady body temperature (heat). Consider challenging your students to come up with additional examples of such common energy conversions.
Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. Teaching Tips 1. In our daily lives, we rely upon many energy transformations. On our classroom walls, a clock converts electrical energy to mechanical energy to sweep the hands around the clock’s face. Our physical (mechanical) activities walking to and from the classroom rely upon the chemical energy from our diet. This chemical energy in our diet also helps us maintain a steady body temperature (heat). Consider challenging your students to come up with additional examples of such common energy conversions.
Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. Teaching Tips 1. In our daily lives, we rely upon many energy transformations. On our classroom walls, a clock converts electrical energy to mechanical energy to sweep the hands around the clock’s face. Our physical (mechanical) activities walking to and from the classroom rely upon the chemical energy from our diet. This chemical energy in our diet also helps us maintain a steady body temperature (heat). Consider challenging your students to come up with additional examples of such common energy conversions.
Figure 5.10A Kinetic energy, the energy of motion.
Figure 5.10B Potential energy, stored energy as a result of location or structure.
Figure 5.10C Potential energy being converted to kinetic energy.
Some scientists study matter within a particular system. Some systems are isolated systems because they are unable to exchange energy or matter with their surroundings. An open system allows energy and matter to be transferred between the system and the surroundings. Organisms are open systems. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. All too often we hear or read that some thing or reaction creates energy. We might hear or read that a power plant “produces” energy or that mitochondria “make” energy. Even in our classroom conversations, we may occasionally slip into this error. When discussing the first law of thermodynamics, consider emphasizing the inaccuracy of such statements. 3. Although typically familiar with the concept of dietary calories, students often struggle to think of calories as a source of potential energy. For many students, it is not clear that potential energy is stored in food as calories. Teaching Tips 1. Some students can relate well to the concept of entropy as applied to the room where they live. Despite cleaning up and organizing the room on a regular (or irregular) basis, the room becomes increasingly disorganized, a victim of entropy, until another energy input (or effort) is exerted to make the room more orderly again. Students might even get to know entropy as the “dorm room effect.” 2. The heat produced by the engine of a car is typically used to heat the car during cold weather. However, is this same heat available in warmer weather? Students are often unaware that their car “heater” works very well in the summer too. Just as exercise can warm us when it is cold, the same extra heat is released when we exercise in warm conditions. A car engine in the summer struggles to dissipate heat in the same way that a human struggles to cool off after exercising when weather is warm. 3. Here is a question that might make cellular respiration a little more meaningful to your students. Ask your students why they feel warm when it is 30°C (86°F) outside if their core body temperature is 37°C (98.6°F). Shouldn’t they feel cold? The answer is, our bodies are always producing heat. At these higher temperatures, we are producing more heat than we need, to maintain a core body temperature around 37°C. Thus, we sweat and behave in ways that help release our extra heat generated in cellular respiration.
In the process of carrying out chemical reactions that provide work for the cell, living cells unavoidably convert organized forms of energy to heat. Therefore, living systems increase the entropy of their surroundings. Some students can relate well to the concept of entropy as it relates to the room where they live. Despite cleaning up and organizing the room on a regular (or irregular) basis, the room increasingly becomes disorganized, a victim of entropy, until another energy input (or effort) is exerted to make the room more orderly again. Students might even get to know “entropy” as the “dorm room effect.” Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. All too often we hear or read that some thing or reaction creates energy. We might hear or read that a power plant “produces” energy or that mitochondria “make” energy. Even in our classroom conversations, we may occasionally slip into this error. When discussing the first law of thermodynamics, consider emphasizing the inaccuracy of such statements. 3. Although typically familiar with the concept of dietary calories, students often struggle to think of calories as a source of potential energy. For many students, it is not clear that potential energy is stored in food as calories. Teaching Tips 1. Some students can relate well to the concept of entropy as applied to the room where they live. Despite cleaning up and organizing the room on a regular (or irregular) basis, the room becomes increasingly disorganized, a victim of entropy, until another energy input (or effort) is exerted to make the room more orderly again. Students might even get to know entropy as the “dorm room effect.” 2. The heat produced by the engine of a car is typically used to heat the car during cold weather. However, is this same heat available in warmer weather? Students are often unaware that their car “heater” works very well in the summer too. Just as exercise can warm us when it is cold, the same extra heat is released when we exercise in warm conditions. A car engine in the summer struggles to dissipate heat in the same way that a human struggles to cool off after exercising when weather is warm. 3. Here is a question that might make cellular respiration a little more meaningful to your students. Ask your students why they feel warm when it is 30°C (86°F) outside if their core body temperature is 37°C (98.6°F). Shouldn’t they feel cold? The answer is, our bodies are always producing heat. At these higher temperatures, we are producing more heat than we need, to maintain a core body temperature around 37°C. Thus, we sweat and behave in ways that help release our extra heat generated in cellular respiration.
Figure 5.11 Energy transformations (with an increase in entropy) in a car and a cell.
Figure 5.11 Energy transformations (with an increase in entropy) in a car.
Figure 5.11 Energy transformations (with an increase in entropy) in a cell.
A car engine in the summer struggles to dissipate heat in the same way that a human struggles to cool off after exercising when weather is warm. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Teaching Tips 1. The same mass of fat stores nearly twice as many calories (about 9 kcal per gram) as an equivalent mass of protein or carbohydrates (about 4.5–5 kcal per gram). Thus, when comparing equal masses of fat, protein, and lipid, the fat has nearly twice the potential energy. Fat is therefore an efficient way to store energy in animals and many plants. To store an equivalent amount of energy in the form of carbohydrates or proteins would require about twice the mass, adding a significant burden to the organism’s structure. (For example, if you were 20 lbs overweight, you would be nearly 40 lbs overweight if the same energy were stored as carbohydrates or proteins instead of fat). 2. The amount of energy each adult human needs to generate the ATP required in a day is tremendous. Here is a calculation that has impressed many students. Depending upon the size and activity of a person, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0° to 100°C. This is something to think about the next time you heat water on the stove! If you can bring in ten 2-liter bottles, you can help students visualize how much liquid water can be raised from 0° to 100°C. (Note: 100 calories raises about 1 liter of water 100°C, but it takes much more energy to melt ice or to convert boiling water into steam.)
Figure 5.12A Exergonic reaction, energy released.
Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Teaching Tips 1. The same mass of fat stores nearly twice as many calories (about 9 kcal per gram) as an equivalent mass of protein or carbohydrates (about 4.5–5 kcal per gram). Thus, when comparing equal masses of fat, protein, and lipid, the fat has nearly twice the potential energy. Fat is therefore an efficient way to store energy in animals and many plants. To store an equivalent amount of energy in the form of carbohydrates or proteins would require about twice the mass, adding a significant burden to the organism’s structure. (For example, if you were 20 lbs overweight, you would be nearly 40 lbs overweight if the same energy were stored as carbohydrates or proteins instead of fat). 2. The amount of energy each adult human needs to generate the ATP required in a day is tremendous. Here is a calculation that has impressed many students. Depending upon the size and activity of a person, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0° to 100°C. This is something to think about the next time you heat water on the stove! If you can bring in ten 2-liter bottles, you can help students visualize how much liquid water can be raised from 0° to 100°C. (Note: 100 calories raises about 1 liter of water 100°C, but it takes much more energy to melt ice or to convert boiling water into steam.)
Figure 5.12B Endergonic reaction, energy required.
Metabolism requires energy, which is taken from sugar or other molecules containing energy. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Teaching Tips 1. The same mass of fat stores nearly twice as many calories (about 9 kcal per gram) as an equivalent mass of protein or carbohydrates (about 4.5–5 kcal per gram). Thus, when comparing equal masses of fat, protein, and lipid, the fat has nearly twice the potential energy. Fat is therefore an efficient way to store energy in animals and many plants. To store an equivalent amount of energy in the form of carbohydrates or proteins would require about twice the mass, adding a significant burden to the organism’s structure. (For example, if you were 20 lbs overweight, you would be nearly 40 lbs overweight if the same energy were stored as carbohydrates or proteins instead of fat). 2. The amount of energy each adult human needs to generate the ATP required in a day is tremendous. Here is a calculation that has impressed many students. Depending upon the size and activity of a person, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0° to 100°C. This is something to think about the next time you heat water on the stove! If you can bring in ten 2-liter bottles, you can help students visualize how much liquid water can be raised from 0° to 100°C. (Note: 100 calories raises about 1 liter of water 100°C, but it takes much more energy to melt ice or to convert boiling water into steam.)
ATP is responsible for mediating most energy coupling in cells. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Teaching Tips 1. The same mass of fat stores nearly twice as many calories (about 9 kcal per gram) as an equivalent mass of protein or carbohydrates (about 4.5–5 kcal per gram). Thus, when comparing equal masses of fat, protein, and lipid, the fat has nearly twice the potential energy. Fat is therefore an efficient way to store energy in animals and many plants. To store an equivalent amount of energy in the form of carbohydrates or proteins would require about twice the mass, adding a significant burden to the organism’s structure. (For example, if you were 20 lbs overweight, you would be nearly 40 lbs overweight if the same energy were stored as carbohydrates or proteins instead of fat). 2. The amount of energy each adult human needs to generate the ATP required in a day is tremendous. Here is a calculation that has impressed many students. Depending upon the size and activity of a person, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0° to 100°C. This is something to think about the next time you heat water on the stove! If you can bring in ten 2-liter bottles, you can help students visualize how much liquid water can be raised from 0° to 100°C. (Note: 100 calories raises about 1 liter of water 100°C, but it takes much more energy to melt ice or to convert boiling water into steam.)
The phosphate group serves as a functional group, and the hydrolysis of this group releases energy. ATP is also one of the nucleoside triphosphates used to make RNA. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Teaching Tips 1. The amount of energy each adult human needs to generate the ATP required in a day is tremendous. Here is a calculation that has impressed many students. Depending upon the size and activity of a person, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0° to 100°C. This is something to think about the next time you heat water on the stove! If you can bring in ten 2-liter bottles, you can help students visualize how much liquid water can be raised from 0° to 100°C. (Note: 100 calories raises about 1 liter of water 100°C, but it takes much more energy to melt ice or to convert boiling water into steam.) 2. When introducing ATP and ADP, consider having them think of the terms as A-3-P and A-2-P, noting that the word roots tri- = 3 and di- = 2. It might help students to keep track of the number of phosphates more easily. 3. Recycling is essential in cell biology. Damaged organelles are broken down intracellularly and chemical components, the monomers of the cytoskeleton, and ADP are routinely recycled. There are several advantages common to human recycling of garbage and cellular recycling. Both save energy by avoiding the need to remanufacture the basic units, and both avoid an accumulation of waste products that could interfere with other “environmental” chemistry (the environment of the cell or the environment of the human population).
For the BLAST Animation ATP/ADP Cycle, go to Animation and Video Files. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Teaching Tips 1. The amount of energy each adult human needs to generate the ATP required in a day is tremendous. Here is a calculation that has impressed many students. Depending upon the size and activity of a person, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0° to 100°C. This is something to think about the next time you heat water on the stove! If you can bring in ten 2-liter bottles, you can help students visualize how much liquid water can be raised from 0° to 100°C. (Note: 100 calories raises about 1 liter of water 100°C, but it takes much more energy to melt ice or to convert boiling water into steam.) 2. When introducing ATP and ADP, consider having them think of the terms as A-3-P and A-2-P, noting that the word roots tri- = 3 and di- = 2. It might help students to keep track of the number of phosphates more easily. 3. Recycling is essential in cell biology. Damaged organelles are broken down intracellularly and chemical components, the monomers of the cytoskeleton, and ADP are routinely recycled. There are several advantages common to human recycling of garbage and cellular recycling. Both save energy by avoiding the need to remanufacture the basic units, and both avoid an accumulation of waste products that could interfere with other “environmental” chemistry (the environment of the cell or the environment of the human population).
Figure 5.13A The structure and hydrolysis of ATP. The reaction of ATP and water yields ADP, a phosphate group, and energy.
Figure 5.13A The structure and hydrolysis of ATP. The reaction of ATP and water yields ADP, a phosphate group, and energy.
Figure 5.13B How ATP powers cellular work.
For the BLAST Animation Structure of ATP, go to Animation and Video Files. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Teaching Tips 1. The amount of energy each adult human needs to generate the ATP required in a day is tremendous. Here is a calculation that has impressed many students. Depending upon the size and activity of a person, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0° to 100°C. This is something to think about the next time you heat water on the stove! If you can bring in ten 2-liter bottles, you can help students visualize how much liquid water can be raised from 0° to 100°C. (Note: 100 calories raises about 1 liter of water 100°C, but it takes much more energy to melt ice or to convert boiling water into steam.) 2. When introducing ATP and ADP, consider having them think of the terms as A-3-P and A-2-P, noting that the word roots tri- = 3 and di- = 2. It might help students to keep track of the number of phosphates more easily. 3. Recycling is essential in cell biology. Damaged organelles are broken down intracellularly and chemical components, the monomers of the cytoskeleton, and ADP are routinely recycled. There are several advantages common to human recycling of garbage and cellular recycling. Both save energy by avoiding the need to remanufacture the basic units, and both avoid an accumulation of waste products that could interfere with other “environmental” chemistry (the environment of the cell or the environment of the human population).
Figure 5.13C The ATP cycle.
Heat could be used to initiate a reaction. However, heat would kill the cell and would not be specific for a particular reaction. For the BLAST Animation Enzymes: Activation Energy, go to Animation and Video Files. Student Misconceptions and Concerns 1. For students not previously familiar with activation energy, analogies can make all the difference. Activation energy can be thought of as a small input that is needed to trigger a large output. This is like (a) an irritated person who needs only a bit more frustration to explode in anger, (b) small waves that lift debris over a dam, or (c) lighting a match around lighter fluid. In each situation, the output is much greater than the input. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids.
Most enzymes are proteins, but RNA enzymes, also called ribozymes, also catalyze reactions. Student Misconceptions and Concerns 1. For students not previously familiar with activation energy, analogies can make all the difference. Activation energy can be thought of as a small input that is needed to trigger a large output. This is like (a) an irritated person who needs only a bit more frustration to explode in anger, (b) small waves that lift debris over a dam, or (c) lighting a match around lighter fluid. In each situation, the output is much greater than the input. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids.
Figure 5.14 The effect of an enzyme is to lower E A .
Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. The text notes that the relationship between an enzyme and its substrate is like a handshake, with each hand generally conforming to the shape of the other. This induced fit is also like the change in shape of a glove when a hand is inserted. The glove’s general shape matches the hand, but the final “fit” requires some additional adjustments.
Figure 5.15 The catalytic cycle of an enzyme.
Figure 5.15 The catalytic cycle of an enzyme.
Figure 5.15 The catalytic cycle of an enzyme.
Figure 5.15 The catalytic cycle of an enzyme.
Certain chemicals also alter enzyme function and have been used to kill bacteria. For the BLAST Animation Enzymes: Types and Specificity, go to Animation and Video Files. Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. The text notes that the relationship between an enzyme and its substrate is like a handshake, with each hand generally conforming to the shape of the other. This induced fit is also like the change in shape of a glove when a hand is inserted. The glove’s general shape matches the hand, but the final “fit” requires some additional adjustments.
We need vitamins in our food or as supplements because of their role in metabolism driven by enzymes. Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. The text notes that the relationship between an enzyme and its substrate is like a handshake, with each hand generally conforming to the shape of the other. This induced fit is also like the change in shape of a glove when a hand is inserted. The glove’s general shape matches the hand, but the final “fit” requires some additional adjustments.
Penicillin, an antibiotic, is an example of a noncompetitive inhibitor because it blocks the active site of an enzyme that some bacteria use to make their cell wall. For the BLAST Animation Enzyme Regulation: Chemical Modification, go to Animation and Video Files. For the BLAST Animation Enzyme Regulation: Competitive Inhibition, go to Animation and Video Files. Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. Enzyme inhibitors that block the active site are like (a) a person sitting in your assigned theater seat or (b) a car parked in your parking space. Analogies for inhibitors that change the shape of the active site are more difficult to imagine. Consider challenging your students to think of such analogies. (Perhaps someone adjusting the driver seat of the car differently from your preferences and then leaving it that way when you try to use the car.) 3. Feedback inhibition relies upon the negative feedback of the accumulation of a product. Ask students in class to suggest other products of reactions that inhibit the process that made them when the product reaches high enough levels. (Gas station pumps routinely shut off when a high level of gasoline is detected. Furnaces typically turn off when enough heat has been produced.) 4. Challenge your class to identify advantages of specific enzyme inhibitors for pest control. These advantages include (a) the ability to target chemical reactions of only certain types of pest organisms and (b) the ability to target chemical reactions that are found in insects but not in humans.
Figure 5.16 How inhibitors interfere with substrate binding.
Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. Enzyme inhibitors that block the active site are like (a) a person sitting in your assigned theater seat or (b) a car parked in your parking space. Analogies for inhibitors that change the shape of the active site are more difficult to imagine. Consider challenging your students to think of such analogies. (Perhaps someone adjusting the driver seat of the car differently from your preferences and then leaving it that way when you try to use the car.) 3. Feedback inhibition relies upon the negative feedback of the accumulation of a product. Ask students in class to suggest other products of reactions that inhibit the process that made them when the product reaches high enough levels. (Gas station pumps routinely shut off when a high level of gasoline is detected. Furnaces typically turn off when enough heat has been produced.) 4. Challenge your class to identify advantages of specific enzyme inhibitors for pest control. These advantages include (a) the ability to target chemical reactions of only certain types of pest organisms and (b) the ability to target chemical reactions that are found in insects but not in humans.
Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. Enzyme inhibitors that block the active site are like (a) a person sitting in your assigned theater seat or (b) a car parked in your parking space. Analogies for inhibitors that change the shape of the active site are more difficult to imagine. Consider challenging your students to think of such analogies. (Perhaps someone adjusting the driver seat of the car differently from your preferences and then leaving it that way when you try to use the car.) 3. Feedback inhibition relies upon the negative feedback of the accumulation of a product. Ask students in class to suggest other products of reactions that inhibit the process that made them when the product reaches high enough levels. (Gas station pumps routinely shut off when a high level of gasoline is detected. Furnaces typically turn off when enough heat has been produced.) 4. Challenge your class to identify advantages of specific enzyme inhibitors for pest control. These advantages include (a) the ability to target chemical reactions of only certain types of pest organisms and (b) the ability to target chemical reactions that are found in insects but not in humans.