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 phospholipid bilayer. The plasma membrane regulates what enters and exits the cell through diffusion, osmosis, facilitated diffusion, active transport, endocytosis, and exocytosis. It also contains proteins that act as carriers, channels, pumps, receptors, enzymes, and adhesion molecules that perform important cell functions.
KEY CONCEPTS
7.1 Cellular membranes are fluid mosaics of lipids and proteins
7.2 Membrane structure results in selective permeability
7.3 Passive transport is diffusion of a substance across a
membrane with no energy investment
7.4 Active transport uses energy to move solutes against their gradients
7.5 Bulk transport across the plasma membrane occurs by exocytosis and endocytosis
Plasma membrane or plasma-lemma or cell membrane
Plasma membrane can be defined as a biological membrane or an outer membrane of a cell, which is composed of two layers of phospholipids and embedded with proteins. It is a thin semi permeable membrane layer, which surrounds the cytoplasm and other constituents of the cell.
Occurs on the outside of the cytoplasm in both prokaryotes and eukaryotic cells.
It separates the cellular protoplasm from its external environment.
cell biology topic transport across cell membrane. transport of important structures accross plasma mebrane of different types of cell in humans. structure and function of cell membane
KEY CONCEPTS
7.1 Cellular membranes are fluid mosaics of lipids and proteins
7.2 Membrane structure results in selective permeability
7.3 Passive transport is diffusion of a substance across a
membrane with no energy investment
7.4 Active transport uses energy to move solutes against their gradients
7.5 Bulk transport across the plasma membrane occurs by exocytosis and endocytosis
Plasma membrane or plasma-lemma or cell membrane
Plasma membrane can be defined as a biological membrane or an outer membrane of a cell, which is composed of two layers of phospholipids and embedded with proteins. It is a thin semi permeable membrane layer, which surrounds the cytoplasm and other constituents of the cell.
Occurs on the outside of the cytoplasm in both prokaryotes and eukaryotic cells.
It separates the cellular protoplasm from its external environment.
cell biology topic transport across cell membrane. transport of important structures accross plasma mebrane of different types of cell in humans. structure and function of cell membane
This presentation include different kind of transport mechanism of different material inside the cell and outside the cell including Passive transport and Active transport mechenism.
Transport mechanisms and their models.JyotiBishlay
It encloses a brief understanding of transportation, its models and different processes likewise, Active and passive transport and their respective mechanisms, i.e. diffusion, osmosis, exocytosis, aquaporins etc.
The plasma membrane, which is also called the cell membrane, has many functions, but the most basic one is to define the borders of the cell and keep the cell functional.
Structure and functions of cell, transport across cell membrane, cell
division, cell junctions. General principles of cell communication,
the smallest unit that can live on its own and that makes up all living organisms and the tissues of the body
The basic tenets of the cell theory are as follows:
All living things are made up of one or more cells.
The cell is the structural and functional unit of all living things.
Cells come from pre-existing cells through the process of division.
All cells are the same in regard to chemical composition.
Cells also communicate with each other. Whether in plants, humans, or animals, they connect to create a solid, well formed organism. In humans, cells build tissues, tissues form organs, and organs work together to keep the body alive.
Experts estimate that there are around 200Trusted Source cell types in the human body.
Waste water treatment is a process used to convert wastewater into an effluent that can be returned to the water cycle with minimum impact on the environment, or directly reused. The latter is called water reclamation because treated wastewater can then be used for other purposes.
Industrial microbiology is a branch of applied microbiology in which microorganisms are used in industrial processes; for example, in the production of high-value products such as drugs, chemicals, fuels and electricity.
An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system. These biotic and abiotic components are linked together through nutrient cycles and energy flows.
Biochemistry, sometimes called biological chemistry, is the study of chemical processes within and relating to living organisms.[1] Biochemical processes give rise to the complexity of life.
Overpopulation is an undesirable condition where the number of existing human population exceeds the carrying capacity of Earth. Overpopulation is caused by number of factors. Reduced mortality rate, better medical facilities, depletion of precious resources are few of the causes which results in overpopulation.
Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity.
Hybridoma technology is a method for producing large numbers of identical antibodies (also called monoclonal antibodies). This process starts by injecting a mouse (or other mammal) with an antigen that provokes an immune response.
Lipids include fats, waxes, phospholipids, sterols, such as cholesterol, and fat-soluble vitamins. Broadly speaking, there are three possible sites where lipids are synthesized: the smooth endoplasmic reticulum (SER), the cytosol and, in plants specifically, the chloroplast.The ER and Golgi apparatus together constitute the endomembrane compartment in the cytoplasm of eukaryotic cells. The endomembrane compartment is a major site of lipid synthesis, and the ER is where not only lipids are synthesized, but membrane-bound proteins and secretory proteins are also made.
There are different bacterial characteristics . These include cultural characteristics, cellular characteristics, and biochemical characteristics. The simplest of these to observe are the cultural characteristics. Learning the cultural characteristics of the organisms we use in the lab will help you greatly, especially when working on your morphological unknown.
the branch of science concerned with the chemical and physico-chemical processes and substances that occur within living organisms.
the processes and substances with which the science of biochemistry is concerned.
The digestion of certain fats begins in the mouth, where short-chain lipids break down into diglycerides because of lingual lipase. The fat present in the small intestine stimulates the release of lipase from the pancreas, and bile from the liver enables the breakdown of fats into fatty acids.
Protein is an important component of every cell in the body. Hair and nails are mostly made of protein. Your body uses protein to build and repair tissues. You also use protein to make enzymes, hormones, and other body chemicals. Protein is an important building block of bones, muscles, cartilage, skin, and blood.
Immune System Organs. The key primary lymphoid organs of the immune system include the thymus and bone marrow, as well as secondary lymphatic tissues including spleen, tonsils, lymph vessels, lymph nodes, adenoids, skin, and liver.
In cellular biology, membrane transport refers to the collection of mechanisms that regulate the passage of solutes such as ions and small molecules through biological membranes, which are lipid bilayers that contain proteins embedded in them.
Antigen-antibody interaction, or antigen-antibody reaction, is a specific chemical interaction between antibodies produced by B cells of the white blood cells and antigens during immune reaction. ... The specificity of the binding is due to specific chemical constitution of each antibody.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
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Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
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Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
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2. Plasma Membrane
Plasma membrane is outer membrane of a cell, which is composed of two layers of
phospholipids and embedded with proteins. It is a thin semi permeable membrane layer,
which surrounds the cytoplasm and other constituents of the cell. The cell membrane also
known as the cell membrane or cytoplasmic membrane, and historically referred to as the
plasma lemma.
Definition of semipermeable. : partially but not freely or wholly permeable; specifically :
permeable to some usually small molecules but not to other usually larger particles.
a semipermeable membrane.
Role of the plasma membrane
All cells are surrounded by a plasma membrane. The membrane is composed of a
phospholipid bilayer arranged back-to-back. The membrane is also covered in places with
cholesterol molecules and proteins. The plasma membrane is selectively permeable and
regulates which molecules are allowed to enter and exit the cell.
3.
4. Structure of plasma membrane
(I) Lipid Bilayer Hypothesis: In Overton (1895) suggested that the cell membranes contain
lipids. This conclusion was based on the fact that fat solvents dissolved the membrane easily
and fat soluble substances passed easily through the cell membranes. Gorter and Grendel
(1925)’ were the first to suggest a possible structure of the cell membrane.
5. (ii) Unit Membrane Model:
In( 1950) J. David Robertson studied the cell membranes from electron micrographs of
sectioned material. The unit membrane is 75 Å thick with a 35 Å thick phospholipid layer
between two 20 Å thick protein layers. The plasma membrane surrounding the cell is thicker
at the free surfaces of the cell than where it is in contact with other cells. In unit membrane
model the protein layers are asymmetrical. On the outer surface it is mucoprotein while on
the inner surface it is non-mucoprotein.
6. (iii) Davson and Danielli : In (1935) The model describes a phospholipid bilayer that lies
between two layers of globular proteins and It is trilaminar and lipoprotinious. In 1935,
Davson and Danielli proposed that biological membranes are made up of lipid bi-layers that
are coated on both sides with thin sheets of protein and they simplified their model into the
"pauci-molecular" theory.
7. (iv) Fluid mosaic model: In (1972), S. Jonathan Singer and Garth Nicolson developed
new ideas for membrane structure. Their proposal was the fluid mosaic model, which is the
dominant model now. It has two key features—a mosaic of proteins embedded in the
membrane, and the membrane being a fluid bi-layer of lipids. The lipid bi-layer suggestion
agrees with previous models but views proteins as globular entities embedded in the layer
instead of thin sheets on the surface. According to the model, membrane proteins are in three
classes based on how they are linked to the lipid bi-layer:
Integral Proteins: Immersed in the bi-layer and held in place by the affinity
of hydrophobic parts of the protein for the hydrophobic tails of phospholipids on interior of
the layer.
Peripheral proteins: More hydrophilic, and thus are non-covalently linked to the polar heads of
phospholipids and other hydrophilic parts of other membrane proteins on the surface of the
membrane.
Lipid anchored proteins: Essentially hydrophilic, so, are also located on the surface of the
membrane, and are covalently attached to lipid molecules embedded in the layer and have
two parts 1."Head": hydrophilic → attracts and mixes with H2O
2.Two "fatty acid tails": hydrophobic
8.
9. Function of plasma membrane-
Protein
Carrier (change shape for different molecules) for water-soluble molecules such as
glucose
Channels for ions (sodium and chloride ions)
Pumps use energy to move water-soluble molecules and ions
Adhesion molecules for holding cells to extracellular matrix
Receptors enable hormones and nerve transmitters to bind to specific cells
Recognition sites, which identify a cell as being of a particular type
Enzymes, which speed up chemical reactions at the edge of the membrane
Adhesion sites, which help some cells to stick together
E.g. glycoprotein acts as a receptor and recognition site
Diffusion
Substances move down their conc. gradient until the conc. are in equilibrium
Microvilli are extensions of the plasma membrane
o They increase the surface area of the membrane, therefore
o They accelerate the rate of diffusion
10. Facilitate diffusion
Trans membrane proteins form a water-filled ion channel
o Allows the passage of ions (Ca2+, Na+, Cl-) down their conc. gradient //passive - no
ATP required
o Some channels use a gate to regulate the flow of ions
o Selective permeability - Not all molecules can pass through selective channels
How do molecules move across the membrane?
o Substrate (molecule to move across the membrane) binds to carrier protein
o Molecule changes shape
o Release of the molecule (product) at the other side of the membrane
Example
o If you want to move a muscle a nerve impulse is sent to this muscle
o The nerve impulse triggers the release of a neurotransmitter
o Binding of the neurotransmitter to specific trans membrane proteins
o Opens channels that allow the passage of Na+ across the membrane
o In this specific case, the result is muscle contraction
o These Na+ channels can also be opened by a change in voltage
11. Osmosis
Special term used for the diffusion of water through a differentially permeable cell
membrane
Water is polar and able to pass through the lipid bilayer
Trans membrane proteins that form hydrophilic channels accelerate osmosis, but water is
still able to get through membrane without them
Osmosis generates pressure called osmotic pressure
o Water moves down its concentration gradient
o When pressure is equal on both sites net flow ceases (equilibrium)
o The pressure is said to be hydrostatic (water-stopping)
Passive Transport-Uses energy from moving particles (Kinetic Energy)
Active Transport
• Movement of solute against the conc. gradient, from low to high conc.
• Involves materials which will not move directly through the bilayer
• Molecules bind to specific carrier proteins / intrinsic proteins
• Involves ATP by cells (mitochondria) / respiration
Direct Active Transport - transporters use hydrolysis to drive active transport
Indirect Active Transport - transporters use energy already stored in gradient of a directly-
pumped ion.
12. Endocytosis and Exocytosis
Substances are transported across plasma membrane in bulk via small vesicles
Endocytosis
o Part of the plasma membrane sinks into the cell
o Forms a vesicle with substances from outside
o Seals back onto the plasma membrane again
Phagocytosis: endocytosis brings solid material into the cell
Pinocytosis: endocytosis brings fluid materials into the cell
Exocytosis
o Vesicle is formed in the cytoplasm
o Moves towards plasma membrane and fuses with plasma membrane
o Contents are pushed outside cell
o Insulin is secreted from cells in this way