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 cell membrane has a fluid mosaic structure, comprising a phospholipid bilayer with embedded proteins. The phospholipid tails face each other at the center of the bilayer to be protected from the watery environments inside and outside the cell, while the phosphate heads face outwards. Transmembrane and peripheral proteins embedded in the bilayer form channels to regulate what passes in and out of the cell. Cholesterol maintains the fluidity and stability of the membrane. The membrane acts as a selectively permeable barrier and facilitates cell structure, communication, recognition, mobility, and chemical reactions.
Gap junctions allow direct communication between adjacent cells by forming channels between the cells' cytoplasm. The structure of a gap junction consists of connexons - cylinders of six transmembrane protein subunits called connexins - arranged back-to-back between the plasma membranes of adjacent cells. These connexons join to form channels about 1.5-2.0 nm in diameter that connect the cytoplasm of the two cells and allow small molecules and ions to pass directly between cells, enabling both electrical and metabolic cooperation.
Membranes cover the surface of cells and surround organelles within cells. They serve several functions including maintaining cellular integrity by keeping components inside, selectively controlling movement of molecules in and out, and allowing cellular processes to occur separately within organelles. The plasma membrane forms the boundary of the cell and is made of a phospholipid bilayer with various embedded and attached proteins and carbohydrates. It regulates what enters and exits the cell.
The document summarizes the key components and structure of the cell membrane according to the fluid mosaic model. It describes that the cell membrane is a lipid bilayer with embedded and associated proteins. The major constituents are phospholipids that form the bilayer, cholesterol that provides stability, and various types of membrane proteins. The fluid mosaic model and experimental evidence demonstrate that the cell membrane is fluid and dynamic in nature.
endocytosis and exocytosis is a procss of cell eating and drinnking. it is a mazor tool for self defence to an individual cell. there are some molecular mechanism for this process described in given notes.
The plasma membrane is a selectively permeable membrane that surrounds the cell. It is composed of a phospholipid bilayer with embedded proteins. The fluid mosaic model describes the plasma membrane structure, with integral and peripheral proteins embedded within or attached to the fluid phospholipid bilayer. The plasma membrane regulates what enters and exits the cell through passive diffusion, facilitated diffusion, active transport, osmosis, and bulk transport mechanisms like endocytosis and exocytosis.
Exocytosis is a form of active transport where a cell transports molecules out of the cell by fusing secretory vesicles containing these molecules to the cell membrane, releasing their contents outside the cell. In neurotransmission, neurotransmitters are typically released from synaptic vesicles via exocytosis. Endocytosis is the opposite process where the cell transports macromolecules into the cell by engulfing them in vesicles. There are different forms of endocytosis, including pinocytosis, where the cell drinks in fluid and particles from the extracellular environment, and phagocytosis, where cells engulf large particles through extension of pseudopodia.
General overview of Plasma/ Cell membrane.
Definition of Plasma/ Cell membrane
Structure of Plasma membrane
1. Sandwitch model ORDanielli- Davson Model
2. Fluid mosaic model
Plasma Membrane Proteins
Chemical Composition of Plasma/ Cell Membrane
Movement across the Cell Membrane
Channels through cell membrane
The cell membrane has a fluid mosaic structure, comprising a phospholipid bilayer with embedded proteins. The phospholipid tails face each other at the center of the bilayer to be protected from the watery environments inside and outside the cell, while the phosphate heads face outwards. Transmembrane and peripheral proteins embedded in the bilayer form channels to regulate what passes in and out of the cell. Cholesterol maintains the fluidity and stability of the membrane. The membrane acts as a selectively permeable barrier and facilitates cell structure, communication, recognition, mobility, and chemical reactions.
Gap junctions allow direct communication between adjacent cells by forming channels between the cells' cytoplasm. The structure of a gap junction consists of connexons - cylinders of six transmembrane protein subunits called connexins - arranged back-to-back between the plasma membranes of adjacent cells. These connexons join to form channels about 1.5-2.0 nm in diameter that connect the cytoplasm of the two cells and allow small molecules and ions to pass directly between cells, enabling both electrical and metabolic cooperation.
Membranes cover the surface of cells and surround organelles within cells. They serve several functions including maintaining cellular integrity by keeping components inside, selectively controlling movement of molecules in and out, and allowing cellular processes to occur separately within organelles. The plasma membrane forms the boundary of the cell and is made of a phospholipid bilayer with various embedded and attached proteins and carbohydrates. It regulates what enters and exits the cell.
The document summarizes the key components and structure of the cell membrane according to the fluid mosaic model. It describes that the cell membrane is a lipid bilayer with embedded and associated proteins. The major constituents are phospholipids that form the bilayer, cholesterol that provides stability, and various types of membrane proteins. The fluid mosaic model and experimental evidence demonstrate that the cell membrane is fluid and dynamic in nature.
endocytosis and exocytosis is a procss of cell eating and drinnking. it is a mazor tool for self defence to an individual cell. there are some molecular mechanism for this process described in given notes.
The plasma membrane is a selectively permeable membrane that surrounds the cell. It is composed of a phospholipid bilayer with embedded proteins. The fluid mosaic model describes the plasma membrane structure, with integral and peripheral proteins embedded within or attached to the fluid phospholipid bilayer. The plasma membrane regulates what enters and exits the cell through passive diffusion, facilitated diffusion, active transport, osmosis, and bulk transport mechanisms like endocytosis and exocytosis.
Exocytosis is a form of active transport where a cell transports molecules out of the cell by fusing secretory vesicles containing these molecules to the cell membrane, releasing their contents outside the cell. In neurotransmission, neurotransmitters are typically released from synaptic vesicles via exocytosis. Endocytosis is the opposite process where the cell transports macromolecules into the cell by engulfing them in vesicles. There are different forms of endocytosis, including pinocytosis, where the cell drinks in fluid and particles from the extracellular environment, and phagocytosis, where cells engulf large particles through extension of pseudopodia.
General overview of Plasma/ Cell membrane.
Definition of Plasma/ Cell membrane
Structure of Plasma membrane
1. Sandwitch model ORDanielli- Davson Model
2. Fluid mosaic model
Plasma Membrane Proteins
Chemical Composition of Plasma/ Cell Membrane
Movement across the Cell Membrane
Channels through cell membrane
The cell membrane, also called the plasma membrane, is a biological membrane that separates the interior of a cell from the outside environment. It is composed primarily of lipids and proteins arranged in a fluid mosaic structure. The lipid bilayer that forms the foundation of the cell membrane is made up of phospholipids with hydrophilic heads and hydrophobic tails. Embedded within this bilayer are transmembrane and peripheral proteins that perform important functions like selective transport, cell signaling, and providing anchoring sites. The fluid mosaic model proposed by Singer and Nicolson in 1972 is widely accepted as it accounts for the fluid and dynamic nature of the cell membrane.
This document discusses cellular vesicles and membrane trafficking. It defines vesicles as membranous sacs that store and transport cellular products or waste. There are three main types of vesicles: secretory vesicles, transport vesicles, and storage vesicles. The document then discusses the mechanisms and proteins involved in vesicle formation, transport, and fusion, including endocytosis, exocytosis, clathrin, adaptor proteins, dynamin, Rab GTPases, and SNARE proteins. It also mentions some diseases related to problems in vesicle trafficking like botulism, tetanus, and familial hypercholesterolemia.
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
Types of transport include passive transport which does not require energy and active transport which uses protein pumps and channels to move substances across membranes. There are several types of active transport including bulk transport, endocytosis, and exocytosis. Endocytosis brings material into the cell through phagocytosis, pinocytosis, or receptor-mediated endocytosis while exocytosis expels material from the cell. Phagocytosis engulfs solid particles, pinocytosis brings in extracellular fluid through membrane invagination, and receptor-mediated endocytosis specifically uptakes substances bound to cell surface receptors. Both endocytosis and exocytosis use vesicle formation and membrane fusion but transport materials in opposite directions with endocytosis importing and exocytosis exporting.
Biological membranes are composed of a lipid bilayer with embedded proteins. They define the boundaries of cells and organelles, and are selectively permeable, allowing passage of some molecules but not others. This selective permeability is important for maintaining concentration gradients between intracellular and extracellular fluid. Membranes contain proteins that function as pumps, channels, and receptors, and are involved in processes like active transport and endocytosis. Membranes are fluid and allow lateral movement of proteins and lipids, but retain an asymmetric composition between inner and outer surfaces.
The document discusses the biological membrane and its chemical composition. It notes that the plasma membrane is the outer boundary of cells, consisting of a double layer of lipid molecules with embedded proteins. The major components of membranes are glycerophospholipids, sphingolipids, and cholesterol. Glycerophospholipids are amphipathic lipids that form the lipid bilayer structure. The fluid mosaic model describes membranes as a fluid structure with lipids and proteins able to move laterally. Membrane proteins can be integral or peripheral, and help with cell functions like transport and signaling. Membrane fluidity is influenced by temperature and lipid composition.
The cell membrane regulates the movement of materials in and out of cells. It is composed of a phospholipid bilayer with proteins, lipids, and carbohydrates embedded. The membrane maintains homeostasis by transporting nutrients into the cell and waste out, while preventing unwanted substances from entering or needed materials from leaving. Transport occurs through diffusion, osmosis, facilitated diffusion, active transport, and bulk transport like endocytosis and exocytosis.
- The document discusses the structure of the cell membrane and cellular junctions.
- It describes the fluid mosaic model of the cell membrane, which proposes that the membrane is composed of a lipid bilayer with proteins embedded and floating within it, giving it a fluid and mosaic-like structure.
- There are two main types of cellular junctions - anchoring junctions, which attach the cell to other cells or the extracellular matrix, and tight junctions, which form a seal between adjacent cell membranes to control what can pass through the space between them.
The plasma membrane defines the boundary of the cell. It is a selectively permeable phospholipid bilayer with embedded proteins. It is composed of 50-75% proteins, 21-50% lipids, and 8% carbohydrates. There are three models that describe its structure: the sandwich model depicts outer and inner protein layers with a phospholipid middle layer; the unit membrane model also has a trilaminar structure but with extended fibrous proteins; the fluid mosaic model views the membrane as a mosaic of integral and peripheral proteins existing within the fluid phospholipid bilayer. The plasma membrane functions to protect the cell, provide shape, regulate transport, receive signals, act as a receptor, and facilitate chemical exchange.
The document discusses the structure and functions of the plasma membrane. It describes the plasma membrane as a phospholipid bilayer composed of phospholipids with hydrophilic heads and hydrophobic tails arranged in a fluid mosaic structure. The membrane contains various proteins that facilitate transport, act as receptors, or perform other functions. The document outlines different types of membrane transport including diffusion, facilitated diffusion, osmosis, bulk transport, and active transport.
The document discusses carbohydrates and their roles in glycoproteins, glycolipids, and proteoglycans. It explains that carbohydrates are covalently attached to proteins or lipids through glycosylation to form these glycoconjugates. Glycosaminoglycans are linear polysaccharides that help form the extracellular matrix. Common examples discussed include hyaluronic acid, chondroitin sulfate, dermatan sulfate, heparan sulfate, and keratan sulfate. Proteoglycans are core proteins with attached glycosaminoglycan chains that interact with extracellular proteins. Glycoproteins have oligosaccharide chains attached to asparagine or serine/threonine residues. Gly
Gap junctions are specialized protein channels that connect adjacent cells and allow communication between them. They are composed of connexin proteins that span the cell membranes and join to form channels between cells. Gap junctions allow small molecules and ions to pass directly between cells to coordinate electrical signaling and metabolic cooperation. They play important roles in tissues like muscle, brain, and heart by facilitating coordinated cell responses.
This document summarizes different types of cell adhesion molecules (CAMs). It discusses cadherins, which are the primary CAMs in adherens junctions and desmosomes. Integrins are heterodimeric receptors that connect the intracellular and extracellular environments and are involved in cell adhesion to the extracellular matrix. The immunoglobulin superfamily of CAMs are calcium-independent transmembrane proteins with immunoglobulin-like domains. Selectins mediate the initial tethering of leukocytes to endothelial cells during inflammation. Cell adhesion molecules play important roles in processes like embryogenesis, immunity, tissue development, and cancer metastasis.
The document provides an overview of cell membranes and movement across cell membranes. It discusses how cell membranes are made of phospholipids, proteins, and other molecules. The membrane separates cells from their surroundings and controls what moves in and out through selective permeability. There are three main types of movement across membranes - passive diffusion, facilitated diffusion, and active transport. Passive diffusion involves hydrophobic molecules moving freely across the membrane, while facilitated diffusion uses protein channels. Active transport moves molecules against their concentration gradient using protein pumps that require ATP. Water movement occurs through osmosis according to concentration gradients.
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 document discusses cell membranes and ion transport. It begins by defining the plasma membrane/cell membrane and its role in regulating materials moving in and out of cells. It then discusses several key topics:
- Membrane models including the fluid mosaic model which describes membranes as lipid bilayers with embedded proteins that move laterally.
- Membrane structure including lipids, proteins, and carbohydrates. Lipids form the bilayer while proteins and carbohydrates provide other functions.
- Membrane functions such as selective permeability, transport mechanisms, and roles of lipids, proteins, and carbohydrates.
- Factors like temperature and lipid composition that influence membrane fluidity.
- Transport
The cell membrane, also called the plasma membrane, is a biological membrane that separates the interior of a cell from the outside environment. It is composed primarily of lipids and proteins arranged in a fluid mosaic structure. The lipid bilayer that forms the foundation of the cell membrane is made up of phospholipids with hydrophilic heads and hydrophobic tails. Embedded within this bilayer are transmembrane and peripheral proteins that perform important functions like selective transport, cell signaling, and providing anchoring sites. The fluid mosaic model proposed by Singer and Nicolson in 1972 is widely accepted as it accounts for the fluid and dynamic nature of the cell membrane.
This document discusses cellular vesicles and membrane trafficking. It defines vesicles as membranous sacs that store and transport cellular products or waste. There are three main types of vesicles: secretory vesicles, transport vesicles, and storage vesicles. The document then discusses the mechanisms and proteins involved in vesicle formation, transport, and fusion, including endocytosis, exocytosis, clathrin, adaptor proteins, dynamin, Rab GTPases, and SNARE proteins. It also mentions some diseases related to problems in vesicle trafficking like botulism, tetanus, and familial hypercholesterolemia.
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
Types of transport include passive transport which does not require energy and active transport which uses protein pumps and channels to move substances across membranes. There are several types of active transport including bulk transport, endocytosis, and exocytosis. Endocytosis brings material into the cell through phagocytosis, pinocytosis, or receptor-mediated endocytosis while exocytosis expels material from the cell. Phagocytosis engulfs solid particles, pinocytosis brings in extracellular fluid through membrane invagination, and receptor-mediated endocytosis specifically uptakes substances bound to cell surface receptors. Both endocytosis and exocytosis use vesicle formation and membrane fusion but transport materials in opposite directions with endocytosis importing and exocytosis exporting.
Biological membranes are composed of a lipid bilayer with embedded proteins. They define the boundaries of cells and organelles, and are selectively permeable, allowing passage of some molecules but not others. This selective permeability is important for maintaining concentration gradients between intracellular and extracellular fluid. Membranes contain proteins that function as pumps, channels, and receptors, and are involved in processes like active transport and endocytosis. Membranes are fluid and allow lateral movement of proteins and lipids, but retain an asymmetric composition between inner and outer surfaces.
The document discusses the biological membrane and its chemical composition. It notes that the plasma membrane is the outer boundary of cells, consisting of a double layer of lipid molecules with embedded proteins. The major components of membranes are glycerophospholipids, sphingolipids, and cholesterol. Glycerophospholipids are amphipathic lipids that form the lipid bilayer structure. The fluid mosaic model describes membranes as a fluid structure with lipids and proteins able to move laterally. Membrane proteins can be integral or peripheral, and help with cell functions like transport and signaling. Membrane fluidity is influenced by temperature and lipid composition.
The cell membrane regulates the movement of materials in and out of cells. It is composed of a phospholipid bilayer with proteins, lipids, and carbohydrates embedded. The membrane maintains homeostasis by transporting nutrients into the cell and waste out, while preventing unwanted substances from entering or needed materials from leaving. Transport occurs through diffusion, osmosis, facilitated diffusion, active transport, and bulk transport like endocytosis and exocytosis.
- The document discusses the structure of the cell membrane and cellular junctions.
- It describes the fluid mosaic model of the cell membrane, which proposes that the membrane is composed of a lipid bilayer with proteins embedded and floating within it, giving it a fluid and mosaic-like structure.
- There are two main types of cellular junctions - anchoring junctions, which attach the cell to other cells or the extracellular matrix, and tight junctions, which form a seal between adjacent cell membranes to control what can pass through the space between them.
The plasma membrane defines the boundary of the cell. It is a selectively permeable phospholipid bilayer with embedded proteins. It is composed of 50-75% proteins, 21-50% lipids, and 8% carbohydrates. There are three models that describe its structure: the sandwich model depicts outer and inner protein layers with a phospholipid middle layer; the unit membrane model also has a trilaminar structure but with extended fibrous proteins; the fluid mosaic model views the membrane as a mosaic of integral and peripheral proteins existing within the fluid phospholipid bilayer. The plasma membrane functions to protect the cell, provide shape, regulate transport, receive signals, act as a receptor, and facilitate chemical exchange.
The document discusses the structure and functions of the plasma membrane. It describes the plasma membrane as a phospholipid bilayer composed of phospholipids with hydrophilic heads and hydrophobic tails arranged in a fluid mosaic structure. The membrane contains various proteins that facilitate transport, act as receptors, or perform other functions. The document outlines different types of membrane transport including diffusion, facilitated diffusion, osmosis, bulk transport, and active transport.
The document discusses carbohydrates and their roles in glycoproteins, glycolipids, and proteoglycans. It explains that carbohydrates are covalently attached to proteins or lipids through glycosylation to form these glycoconjugates. Glycosaminoglycans are linear polysaccharides that help form the extracellular matrix. Common examples discussed include hyaluronic acid, chondroitin sulfate, dermatan sulfate, heparan sulfate, and keratan sulfate. Proteoglycans are core proteins with attached glycosaminoglycan chains that interact with extracellular proteins. Glycoproteins have oligosaccharide chains attached to asparagine or serine/threonine residues. Gly
Gap junctions are specialized protein channels that connect adjacent cells and allow communication between them. They are composed of connexin proteins that span the cell membranes and join to form channels between cells. Gap junctions allow small molecules and ions to pass directly between cells to coordinate electrical signaling and metabolic cooperation. They play important roles in tissues like muscle, brain, and heart by facilitating coordinated cell responses.
This document summarizes different types of cell adhesion molecules (CAMs). It discusses cadherins, which are the primary CAMs in adherens junctions and desmosomes. Integrins are heterodimeric receptors that connect the intracellular and extracellular environments and are involved in cell adhesion to the extracellular matrix. The immunoglobulin superfamily of CAMs are calcium-independent transmembrane proteins with immunoglobulin-like domains. Selectins mediate the initial tethering of leukocytes to endothelial cells during inflammation. Cell adhesion molecules play important roles in processes like embryogenesis, immunity, tissue development, and cancer metastasis.
The document provides an overview of cell membranes and movement across cell membranes. It discusses how cell membranes are made of phospholipids, proteins, and other molecules. The membrane separates cells from their surroundings and controls what moves in and out through selective permeability. There are three main types of movement across membranes - passive diffusion, facilitated diffusion, and active transport. Passive diffusion involves hydrophobic molecules moving freely across the membrane, while facilitated diffusion uses protein channels. Active transport moves molecules against their concentration gradient using protein pumps that require ATP. Water movement occurs through osmosis according to concentration gradients.
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 document discusses cell membranes and ion transport. It begins by defining the plasma membrane/cell membrane and its role in regulating materials moving in and out of cells. It then discusses several key topics:
- Membrane models including the fluid mosaic model which describes membranes as lipid bilayers with embedded proteins that move laterally.
- Membrane structure including lipids, proteins, and carbohydrates. Lipids form the bilayer while proteins and carbohydrates provide other functions.
- Membrane functions such as selective permeability, transport mechanisms, and roles of lipids, proteins, and carbohydrates.
- Factors like temperature and lipid composition that influence membrane fluidity.
- Transport
Membrane structure and membrane chemistry.pptxrajashri101
The document discusses membrane structures, specifically plasma membranes. It begins by explaining that plasma membranes hold the cell together and act as a barrier, being composed of a phospholipid bilayer with embedded and peripheral proteins. It then provides details on the fluid mosaic model of membrane structure, which proposes that membranes are a fluid bilayer of lipids with globular proteins dispersed within. The functions of plasma membranes are then outlined, including compartmentalization, selectively permitting transport, responding to signals, and mediating cell-cell interactions through receptors.
The document discusses the structure and functions of cell membranes. It notes that membranes are composed of phospholipids, glycolipids, cholesterol and proteins. Membranes form a selectively permeable barrier and establish concentration gradients. They localize enzymes and processes like transport, signaling, endocytosis and exocytosis. The fluid mosaic model describes membranes as a fluid structure with proteins embedded and diffusing. Membrane composition and fluidity impact functions like signaling, vesicle movement and cell division.
Membranes cover the surface of cells and surround organelles within cells. They have several functions, including keeping cellular components inside the cell, allowing selective movement of molecules in and out, isolating organelles, and allowing cells to change shape. The plasma membrane forms the outer boundary of cells and is composed of a phospholipid bilayer with various embedded and attached proteins and carbohydrates. It regulates what moves in and out of cells.
The cell membrane is composed of a bilayer of lipids and embedded proteins. The lipid bilayer provides structural organization with phospholipids as the major component. Proteins constitute 25-75% of the membrane mass and carry out specific functions. The membrane is selectively permeable due to transport proteins that regulate the passage of molecules. Transport proteins include channel proteins that form pores and carrier proteins that selectively bind molecules. In addition to transport, membrane proteins are involved in cell recognition, cell adhesion, and cell signaling.
The plasma membrane is a phospholipid bilayer that forms the boundary of cells. It is selectively permeable, allowing some substances to pass through more easily than others. Early models proposed that proteins were sandwiched between phospholipid layers, but the fluid mosaic model established in 1972 described proteins as being dispersed within and moving laterally through the fluid phospholipid bilayer. Membrane proteins have important functions including transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, and attachment to intracellular and extracellular structures. Membranes are synthesized in the ER and Golgi apparatus and their structure results in the selective permeability that allows cells to exchange materials with their surroundings.
The document summarizes key aspects of cell membrane structure and function. It describes the fluid mosaic model of the membrane structure consisting of a phospholipid bilayer with embedded proteins. It discusses the components of the membrane including phospholipids, cholesterol, and carbohydrates. It explains the major functions of membrane proteins including transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, and attachment to the cytoskeleton. It also summarizes the different types of transport processes like diffusion, facilitated diffusion, active transport and examples of transport proteins and mechanisms.
Cell for teaching by pandian M tutor, Dept of Physiology, DYPMCKOP, this ppt ...Pandian M
The cell
Common characteristics of cell –
Typical cell under light microscope
Cell organelles –
6 main types of organelles
Mitochondria
Endocytosis
Receptor mediated endocytosis
Phagocytosis
Functional systems of the cell—
Intercellular connections or junctions
Basic mechanism of transport
References
The plasma membrane is a selectively permeable barrier that surrounds cells and regulates what passes into and out. It is made up of a lipid bilayer with phospholipids, cholesterol, and glycolipids embedded with integral and peripheral proteins. The fluid mosaic model describes the membrane as a fluid bilayer with proteins diffusing freely within it. Membrane proteins function as channels, transporters, receptors, enzymes, and markers of cell identity. The lipid bilayer forms a hydrophobic barrier that allows only small, nonpolar substances to pass through, while proteins facilitate selective passage of ions and molecules into and out of the cell.
This document provides an overview of cell biology, covering key topics such as:
1. The different types of microscopes used to study cells and their relative capabilities.
2. The main differences between prokaryotic and eukaryotic cells, including their genetic material and internal structures.
3. The structures and functions of eukaryotic cell organelles such as the nucleus, mitochondria, chloroplasts, Golgi apparatus, endoplasmic reticulum, and cytoskeleton. These organelles allow for compartmentalization and specialized functions within eukaryotic cells.
The plasma membrane is a lipid bilayer with proteins embedded within it. It forms the boundary between a cell and its external environment. The fluid mosaic model describes the plasma membrane as having phospholipids that form a bilayer, within which proteins and other molecules like cholesterol are embedded. This allows the membrane to be fluid and flexible. Membrane proteins can be intrinsic, spanning the membrane, or extrinsic, attached to one surface. Together, the lipids and proteins allow the selective control of what enters and exits the cell.
The document summarizes key differences between prokaryotic and eukaryotic cells. Prokaryotic cells, which lack a nucleus, are typically smaller than eukaryotic cells and do not have internal subcellular structures like organelles. In contrast, eukaryotic cells have a well-defined nucleus that contains DNA, as well as distinct organelles such as mitochondria and lysosomes that carry out specialized functions. The document also provides details on the structure and functions of various eukaryotic cell organelles.
The document summarizes key aspects of cellular structure and function. It describes the basic components of cells, including the cell membrane, cytoplasm, and nucleus. Specifically, it discusses the structure and properties of the cell membrane, including its fluid mosaic model consisting of lipids and proteins. It also describes the cytoplasm and some of its major organelles, focusing on the endoplasmic reticulum. The functions of the cell membrane are also summarized, such as its role in transport, protection, receiving stimuli, and metabolic processes.
This document provides an overview of cell structure and function. It discusses the structure and functions of cellular organelles like the cell membrane, mitochondria, endoplasmic reticulum, lysosomes, peroxisomes, and cytoskeleton. It also describes intercellular junctions and cell adhesion molecules. A case study example is provided to illustrate glycogen storage disorder.
The document summarizes key components and functions of the cell membrane and cytoplasm. It describes the cell membrane as a selectively permeable phospholipid bilayer that envelops the cell. It also discusses the fluid mosaic model of the cell membrane and its integral and peripheral proteins. The cytoplasm is described as containing a cytosol and various organelles, including the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, and cytoskeleton. Various types of transport across the cell membrane, such as diffusion, osmosis, facilitated diffusion, and active transport, are also summarized.
The document summarizes key aspects of culturing cells outside of their native biological environment. Cultured cells experience changes to their microenvironment, cell-cell interactions, and exposure to stimuli. Their growth is influenced by factors like the substrate, medium composition, temperature, and gas phase. Most cells require attachment to a substrate to proliferate. Adhesion molecules like integrins and cadherins mediate attachment and formation of intercellular junctions. The extracellular matrix and cytoskeleton also influence cell behavior. Control of the cell cycle, proliferation, differentiation, motility, and response to the culture environment are described at a high level. Challenges like dedifferentiation and evolution of cell lines over multiple passages are also covered.
membrana celular y sus componentes estructurarlesbrayancriollo6
The cell membrane is a selectively permeable phospholipid bilayer that separates the cell from its surroundings. It is described by the fluid mosaic model as a fluid structure composed of phospholipids and various embedded proteins. Transport proteins allow for selective passage of substances across the membrane through channels or carrier proteins. Membrane structure results in selective permeability, with hydrophobic molecules able to pass through the lipid bilayer and transport proteins facilitating passage of hydrophilic substances down concentration gradients through passive diffusion.
The document discusses several key functions and properties of cell membranes:
- It describes how the fluidity of membranes allows for lateral movement of lipids and proteins, and is influenced by temperature and fatty acid composition.
- The major functions of cell membranes are to regulate passage of substances, detect chemical messengers, link adjacent cells, and anchor cells.
- Transport across membranes can occur through passive diffusion, facilitated diffusion using channel proteins, or active transport using carrier proteins that require ATP.
- Membranes also allow vesicular transport of larger molecules via endocytosis and exocytosis.
- Osmosis allows for diffusion of water across membranes down its concentration gradient. Tonicity refers to cell volume changes in different solutions.
Similar to 05 lecture ppt membrance structure and Function (20)
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This document discusses motivation and the stages of change model as it relates to addiction recovery and relapse prevention. It describes the five stages of change: precontemplation, contemplation, preparation, action, and maintenance. Relapse is presented as being related to motivation and the stages of change. Urge surfing and identifying triggers are taught as skills to manage cravings and prevent relapse. The relationship between emotion, motivation, and challenges in making changes is explored.
This document outlines the agenda for a women's recovery empowerment meeting. It includes activities like quiet time, check-ins where participants share their name, feelings, and last drug/alcohol use. It also involves decorating binders, telling life stories using a lifeline as a reference, and creating clean copies of stories to add to over time. The overall goal is to empower and support women through sharing experiences and creative self-expression.
The document discusses how emotions play a big role in addiction and the powerful connection between emotion and addiction. It describes how drugs of abuse hijack the brain's reward and punishment system, confusing the drug reward with the body's own chemical rewards. Certain brain regions like the prefrontal cortex and limbic structures help regulate emotion. Specific drugs like alcohol, nicotine, methamphetamine, and marijuana impact the brain and neurotransmitters like dopamine in ways that influence emotions, feelings of pleasure, and memory formation, contributing to drug addiction.
Nucleophilic Addition of carbonyl compounds.pptxSSR02
Nucleophilic addition is the most important reaction of carbonyls. Not just aldehydes and ketones, but also carboxylic acid derivatives in general.
Carbonyls undergo addition reactions with a large range of nucleophiles.
Comparing the relative basicity of the nucleophile and the product is extremely helpful in determining how reversible the addition reaction is. Reactions with Grignards and hydrides are irreversible. Reactions with weak bases like halides and carboxylates generally don’t happen.
Electronic effects (inductive effects, electron donation) have a large impact on reactivity.
Large groups adjacent to the carbonyl will slow the rate of reaction.
Neutral nucleophiles can also add to carbonyls, although their additions are generally slower and more reversible. Acid catalysis is sometimes employed to increase the rate of addition.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
ANAMOLOUS SECONDARY GROWTH IN DICOT ROOTS.pptxRASHMI M G
Abnormal or anomalous secondary growth in plants. It defines secondary growth as an increase in plant girth due to vascular cambium or cork cambium. Anomalous secondary growth does not follow the normal pattern of a single vascular cambium producing xylem internally and phloem externally.
2. 2
Outline
• 5.1 Plasma Membrane Structure and
Function
• 5.2 Passive Transport Across a Membrane
• 5.3 Active Transport Across a Membrane
• 5.4 Modification of Cell Surfaces
3. 5.1 Plasma Membrane
Structure and Function
• The plasma membrane is common to all cells
• Separates:
Internal cytoplasm from the external environment of
the cell
• Phospholipid bilayer:
External surface lined with hydrophilic polar heads
Cytoplasmic surface lined with hydrophilic polar
heads
Nonpolar, hydrophobic, fatty-acid tails sandwiched in
between
3
4. Plasma Membrane Structure
and Function
• Components of the Plasma Membrane
Three components:
• Lipid component referred to as phospholipid
bilayer
• Protein molecules
– Float around like icebergs on a sea
– Membrane proteins may be peripheral or
integral
» Peripheral proteins are found on the inner
membrane surface
» Integral proteins are partially or wholly
embedded (transmembrane) in the
membrane
• Cholesterol affects the fluidity of the membrane
4
6. Plasma Membrane Structure
and Function
• Carbohydrate Chains
Glycoproteins
• Proteins with attached carbohydrate chains
Glycolipids
• Lipids with attached carbohydrate chains
These carbohydrate chains exist only on the
outside of the membrane
• Makes the membrane asymmetrical
6
8. Plasma Membrane Structure
and Function
• Functions of Membrane Proteins
Channel Proteins:
• Allow passage of molecules through membrane via a
channel in the protein
Carrier Proteins:
• Combine with the substance to be transported
• Assist passage of molecules through membrane
Cell Recognition Proteins:
• Glycoproteins
• Help the body recognize foreign substances
8
9. Plasma Membrane Structure
and Function
• Functions of Membrane Proteins (continued)
Receptor Proteins:
• Bind with specific molecules
• Allow a cell to respond to signals from other cells
Enzymatic Proteins:
• Carry out metabolic reactions directly
Junction Proteins:
• Attach adjacent cells
9
17. How Cells Talk to One
Another
• Signaling molecules serve as chemical
messengers allowing cells to communicate with
one another
Cell receptors bind to specific signaling molecules
Once the signaling molecule and the cell receptor
bind a cascade of events occurs that elicits a cellular
response
• Signal transduction pathway
17
19. Plasma Membrane Structure
and Function
• Permeability of the Plasma Membrane
The plasma membrane is selectively permeable
• Allows some substances to move across the membrane
• Inhibits passage of other molecules
Small, non-charged molecules (CO2, O2, glycerol,
alcohol) freely cross the membrane by passing
through the phospholipid bilayer
• These molecules follow their concentration gradient
– Move from an area of high concentration to an area of
low concentration.
19
20. Plasma Membrane Structure
and Function
• Permeability of the Plasma Membrane
Water moves across the plasma membrane
• Specialized proteins termed aquaporins speed up water
transport across the membrane
The movement of ions and polar molecules across
the membrane is often assisted by carrier proteins
Some molecules must move against their
concentration gradient with the expenditure of energy
• Active transport
Large particles enter or exit the cell via bulk transport
• Exocytosis
• Endocytosis
20
27. 5.2 Passive Transport Across
a Membrane
• A solution consists of:
A solvent (liquid), and
A solute (dissolved solid)
• Diffusion
Net movement of molecules down a concentration
gradient
Molecules move both ways along gradient, but net
movement is from high to low concentration
Equilibrium:
• When NET movement stops
• Solute concentration is uniform – no gradient
27
32. Passive Transport Across a
Membrane
• Osmosis:
Special case of diffusion
Focuses on solvent (water) movement rather than
solute
Diffusion of water across a selectively permeable
membrane
• Solute concentration on one side is high, but water
concentration is low
• Solute concentration on other side is low, but water
concentration is high
Water can diffuse both ways across membrane but
the solute cannot
Net movement of water is toward low water (high
solute) concentration
• Osmotic pressure is the pressure that develops
due to osmosis
32
34. Passive Transport Across a
Membrane
• Isotonic Solutions
Solute and water concentrations are equal on
both sides of membrane
No net gain or loss of water by the cell
• Hypotonic Solutions
Concentration of solute in the solution is lower
than inside the cell
Cells placed in a hypotonic solution will swell
• Causes turgor pressure in plants
• May cause animal cells to lyse (rupture)
34
35. Passive Transport Across a
Membrane
• Hypertonic Solutions
Concentration of solute is higher in the
solution than inside the cell
Cells placed in a hypertonic solution will
shrink
• Crenation in animal cells
• Plasmolysis in plant cells
35
37. Passive Transport Across a
Membrane
Facilitated Transport
• Movement of molecules that cannot pass directly
through the membrane lipids
• These molecules must combine with carrier
proteins to move across the membrane
• Follow concentration gradient, moving from high
concentration to low concentration
37
42. 5.3 Active Transport Across a
Membrane
Active Transport
• The movement of molecules against their
concentration gradient
– Movement from low to high concentration
• Movement is facilitated by carrier proteins
• Requires the expenditure of energy in the form of
ATP
• Ex: sodium-potassium pump
– Uses ATP to move sodium ions out of the cells and
potassium ions into the cell against their concentration
gradients.
42
49. Active Transport Across a
Membrane
• Macromolecules are transported into or out of
the cell inside vesicles via bulk transport
Exocytosis – Vesicles fuse with plasma membrane
and secrete contents
Endocytosis – Cells engulf substances into a pouch
which becomes a vesicle
• Phagocytosis – Large, solid material is taken in by
endocytosis
• Pinocytosis – Vesicles form around a liquid or very small
particles
• Receptor-Mediated Endocytosis– Specific form of
pinocytosis using receptor proteins and a coated pit
49
52. 5.4 Modifications of Cell
Surfaces
• Cell Surfaces in Animals
Extracellular Matrix (ECM)
• Meshwork of proteins and polysaccharides in close
connection with the cell that produced them
– Collagen – resists stretching
– Elastin – provides resilience to the ECM
– Integrin – play role in cell signaling
– Proteoglycans – regulate passage of material through
the ECM to the plasma membrane
52
56. Modifications of Cell Surfaces
• Plant Cell Walls
Plants have a freely permeable cell wall, with
cellulose as the main component
• Plasmodesmata penetrate the cell wall
• Each contains a strand of cytoplasm
• Allow passage of material between cells
56