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Topic: Cell membrane

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In the News (Thu 20 Jun 19)

  Cell membrane fusion
Cellular membrane fusion is well known to scientists, and is one of the most common ways for molecules to enter or exit cells, in processes such as fertilization and viral infection, for example.
When two cells fuse together, their membranes come together at one location and create a connection between the cells that allows the exchange of material between them.
Each membrane is made of a double layer of phospholipids which intermingle to create a passage between the cells.
www.bnl.gov /bnlweb/pubaf/pr/2002/bnlpr091202.htm   (780 words)

Proteins on the inside surface of cell membranes are often attached to the cytoskeleton and are involved in maintaining the cell's shape, or in cell motility.
Cell membranes are a barrier to most substances, and this property allows materials to be concentrated inside cells, excluded from cells, or simply separated from the outside environment.
Cells in marine environments are surrounded by a hypertonic solution, and must actively pump ions into their cells to reduce their water potential and so reduce water loss by osmosis.
www.biologymad.com /cells/cellmembrane.htm   (1771 words)

  Cell membrane - Wikipedia, the free encyclopedia
The foundation is a phospholipid bilayer, and the membrane as a whole is often described as a fluid mosaic – a two-dimensional fluid of freely diffusing lipids, dotted or embedded with proteins, which may function as channels or transporters across the membrane, or as receptors.
The outer cell membrane and the membranes surrounding inner cell organelles are bilipid layers.
As a lipid bilayer, the cell membrane is semi-permeable.
en.wikipedia.org /wiki/Cell_membrane   (1239 words)

 Cell Membrane
The outer cell membrane and the membranes surrounding inner cell organelles are bilipid layers.
The membrane is approximately 5 nanometres thick.(a nanometre is a billionth of a metre thick)
Membrane proteins diffuse throughout the membrane in the same fashion, though at a slower pace because of their relatively massive size compared to a phospholipid molecule.
www.jdaross.cwc.net /cell2.htm   (1070 words)

 Teachers' Domain: Cell Membrane: Just Passing Through
The cell membrane is critical to the survival of a cell.
Like the drawstring opening of a cloth bag, the openings in the cell membrane allow the cell to take in and release fairly large molecules like glucose, as well as ions (atoms with a positive or negative electrical charge) that are unable to pass through the main, lipid-bilayer portion of the membrane.
Depending on the type of molecule or particle involved and the environment inside and outside the membrane, the cell may have to actively pump molecules or ions along the channel in a process called active transport.
www.teachersdomain.org /9-12/sci/life/cell/membraneweb/index.html   (608 words)

 UCMP Glossary: Cell biology
The cell consists primarily of an outer plasma membrane, which separates it from the environment; the genetic material (DNA), which encodes heritable information for the maintainance of life; and the cytoplasm, a heterogeneous assemblage of ions, molecules, and fluid.
Plants are known for their cell walls of cellulose, as are the green algae and certain protists, while fungi have cell walls of chitin.
This is believed to be the result of endosymbiosis, with the outer membrane coming from the eukaryotic cell, and the inner membrane belonging to the original prokaryote which was "swallowed".
www.ucmp.berkeley.edu /glossary/gloss4cell.html   (1470 words)

 Cell Membranes and Snow!
Cell membranes are specially designed to take in water, glucose, and other such materials, without letting "xeno-chemicals" into the cell.
A cell membrane is construted in layers -- the innermost and outermost layers both being made from lipids, and the middle layer in some cells is made from steroids.
Peripheral protiens are in both the interior and exterior surfaces of the cell membrane, held by a weak bond to other protiens in the lipid bilayer.
www.geocities.com /ladywolfb2c/membrane.html   (771 words)

 Cell Membranes
The plasma membrane serves as the interface between the machinery in the interior of the cell and the extracellular fluid (ECF) that bathes all cells.
Phospholipids are amphiphilic with the hydrocarbon tail of the molecule being hydrophobic; its polar head hydrophilic.
Furthermore, those that project into the aqueous surroundings of the cell are usually glycoproteins, with many hydrophilic sugar residues attached to the part of the polypeptide exposed at the surface of the cell.
users.rcn.com /jkimball.ma.ultranet/BiologyPages/C/CellMembranes.html   (446 words)

 Cell Membrane
Membranes are the "skins" of the body cells; they hold the cell together, maintaining shape and preventing loss of components of the cell to its environment.
The hydrophilic outer and inner surfaces of the membrane are coated with a stable crystal lattice of water.
This altered G protein migrates in the plane of the membrane to the catalytic area of the enzyme, which is in an inactive, noncatalytic state.
chemo.net /cell.htm   (1765 words)

 Botany online: Membranes and Transport
Without them would the cell contents diffuse into their surroundings, information containing molecules would be lost and the metabolic pathways would seek a thermal equilibrium: the death of each living system.
This structure lends a tendency to form organized structures and monomolecular layers whose degree of organization is dependent on the length of the fatty acid residues and the number of double bonds to phospholipids.
Membranes separate reaction areas that can be distinguished due to their chemical composition, their pH value and their electric potential.
www.biologie.uni-hamburg.de /b-online/e22/22.htm   (1136 words)

 Using Bubbles to Explore Membranes
Students are asked to learn about cell structures and how they function in a variety of ways, ranging from memorization, to microscope work, to actual lab experiences.
The importance of the cell membrane is usually stressed, but is hard to visualize for most tenth grade biology students.
Have the students form an opening in the membrane by floating a circle of thread on the film, popping the inside of it and then gently removing it.
www.accessexcellence.org /AE/AEC/AEF/1995/wardell_membranes.html   (891 words)

 Cell Membranes   (Site not responding. Last check: 2007-11-07)
While the plant cell has a rigid cell wall, an animal cell membrane is a flexible lipid bilayer.
What makes the membrane truly special is the presence of different proteins on the surface that are used for various functions such as cell surface receptors, enzymes, surface antigens, and transporters.
The lipid content of the membrane allows the cell membrane to automatically repair itself when it is torn.
library.thinkquest.org /C004535/cell_membranes.html   (630 words)

 The Cell Membrane
However, unlike the bark of a tree, which is hard and static, the cell membrane is a fatty, flexible boundary that keeps the cell as an entity.
Receptors are microscopic, folded, protein structures that are transmembranal (they extend across the cell membrane, from the outside of the cell to the cell interior).
To the innermost sanctum of the cell, the nucleus and genes.
www.wholepsych.com /private/CellMembrane.html   (797 words)

 What is a Cell
The simplest of cells, and the first types of cells to evolve, were prokaryotic cells—organisms that lack a nuclear membrane, the membrane that surrounds the nucleus of a cell.
The cells may be adjacent to one another because they did not separate after cell division or because they remained enclosed in a common sheath or slime secreted by the cells.
This membrane serves to separate and protect a cell from its surrounding environment and is made mostly from a double layer of proteins and lipids, fat-like molecules.
www.ncbi.nlm.nih.gov /About/primer/genetics_cell.html   (8545 words)

 Cell Membrane   (Site not responding. Last check: 2007-11-07)
The cell membrane is made up of three parts, phosholipids which are magenta and green, the proteins which are orange and red, and the carbohydrates which are fl.
It is not unusual for carbohydrates, or sugars, to attach to the cell membrane phospolipids and proteins.
The cell membrane regulate's the exchange of vital substances between the content of the cells and it external enviroment.
sun.menloschool.org /~cweaver/cells/e/cell_membrane   (329 words)

 Chapter 2.1: Phospholipid/Cell Membrane   (Site not responding. Last check: 2007-11-07)
The phospholipid bilayer which the cell membrane is an example of, is composed of various cholesterol, phospholipids, glycolipids and proteins.
And since most of the cell and area surrounding the cell is made up of water, these fatty acid tails always 'push' away from the water.
Cholesterol is a major component of cell membranes and serves many other functions as well.
cbri.umn.edu /~mwd/cell_www/chapter2/membrane.html   (579 words)

 Membrane Structure and Function
Membranes are vital because they separate the cell from the outside world.
Plasma membranes of human red blood cells and mouse liver contain nearly equal amounts of proteins (44, 49% respectively) and lipids (43, 52% respectively).
This fracture plane is inbetween the leaflets of the lipid bilayer, as shown by this cartoon.
cellbio.utmb.edu /cellbio/membrane_intro.htm   (1761 words)

 The Cell Membrane   (Site not responding. Last check: 2007-11-07)
The cell membrane is probably the most important organelle in the cell.
Cell membrane is mobile and moves along "grooves" which are set paths the membrane follow.
The cell membrane is composed of a phospholipid bilayer, which has hydrophlic heads that are soluble in water and hydrophobic tails which are not soluble in water.
www.stemnet.nf.ca /~dpower/cell/mbrane.htm   (423 words)

 Plasma Membrane1
Image of Plasma Membrane - A large cartoon image of a cell membrane, followed by an in depth discussion on each component making up the membrane, the chemical compounds present, and the mechanisms which the plasma membrane carries out.
Membrane Proteins - Focuses its discussion of transmembrane proteins, includes discussions on background information, transmembrane protein structure, and their roles in the cell.
A vesicle forms after the cell pinches off the infolded membrane, and the enclosed materials are then sorted to the interior of the cell.
darwin.nmsu.edu /~molbio/cell/PM.html   (1098 words)

 Cell Membrane   (Site not responding. Last check: 2007-11-07)
The cell membrane is responsible, along with the cell wall, for maintaining a balance between the outside world and the inside the cell.
The cell membrane is a selectively permeable barrier that allows some substances to pass through to the inside of the cell while keeping others out.
In order to understand how the cell membrane functions to regulate flow into and out of a cell, it is important to understand the structure of a typical membrane.
crystal.uah.edu /~carter/osmosis/membrane.htm   (273 words)

 Cell Membranes
The permeability of the plasma membrane varies inversely with the size of the molecule -- indicating that the pores are small and the membrane acts like a sieve.
Cells in a marine environment are generally isotonic with its salty water.
Cells of plants and animals are frequently connected in order to communicate and share resources.
home.earthlink.net /~dayvdanls/cell_membranes.htm   (1371 words)

 SparkNotes: Cell Membranes: Membrane Proteins
As we discussed in the previous section, membrane proteins are free to move within the lipid bilayer as a result of its fluidity.
Membrane proteins perform various functions, and this diversity is reflected in the significantly different types of proteins associated with the lipid bilayer.
The protein and lipid cell membrane is covered with a layer of carbohydrate chains on its outer surface.
www.sparknotes.com /biology/cellstructure/cellmembranes/section2.rhtml   (484 words)

 The Cell Membrane
The cell is highly organized with many functional units or organelles.
To perform the function of the organelle, the membrane is specialized in that it contains specific proteins and lipid components that enable it to perform its unique roles for that cell or organelle.
In essence membranes are essential for the integrity and function of the cell.
cellbio.utmb.edu /cellbio/membrane.htm   (412 words)

 The Cell Membrane   (Site not responding. Last check: 2007-11-07)
The cell membrane is probably the most important organelle in the cell.
Cell membrane is mobile and moves along "grooves" which are set paths the membrane follow.
The cell membrane is composed of a phospholipid bilayer, which has hydrophlic heads that are soluble in water and hydrophobic tails which are not soluble in water.
www.cdli.ca /~dpower/cell/mbrane.htm   (423 words)

The beta-subunit is a glycoprotein, with the carbohydrate on the external surface of the membrane.
Cells which are sensitive to steroid hormones have specific receptor proteins in the cytosol or nucleus which bind the steroid.
The receptor-insulin complex migrates to a region of the plasma membrane with the protein clathrin coating its inner surface.
library.med.utah.edu /NetBiochem/membrane.htm   (2845 words)

 cell membrane
The membrane surrounding the cytoplasm of a cell, consisting of a lipid bilayer with embedded proteins.
It regulates what enters and leaves the cell, maintains the correct intracellular pH level, and provides a means of separating charges so that the cell can, for example, generate the energy-carrying molecule adenosine triphosphate.
The cell membrane is both a physical and chemical barrier which defines the boundary between the individual and its environment.
www.daviddarling.info /encyclopedia/C/cellmem.html   (154 words)

 Cell membrane - definition from Biology-Online.org
(Science: cell biology) The structure enveloping a cell, enclosing the cytoplasm and forming a selective permeability barrier.It is inside the cell wall in plant cells, while it is the only barrier between the outside of the cell and the cytoplasm in animal cells.
a thin membrane around the cytoplasm of a cell; controls passage of substances also known as the plasma membrane, that has a structure known as the fluid mosaic model.
The cell membrane is designed to protect the cell,through selective permeability, which is a regulatory function where the membrane determines what amounts and types of molecules can enter and leave the cell.
www.biology-online.org /dictionary/Cell_membrane   (226 words)

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