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∙ 7y agopermeabiity
Chanel Huels
Tarikul Islam
Heather Tremblay
permeability
Keely Brakus
permeability
Gillian Watsica
permeability
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∙ 12y agopermeability
mia landefort
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∙ 12y agopermeability
Whether molecules are able to pass through the membrane depends on the size of the molecules. Smaller ones can, and larger ones cannot. Glucose can pass through a cell membrane because it is a monomer, which is a smaller molecule than the polymer molecules of starch.
In all cells, the cell membrane acts as a combination of brick wall, window, and security guard.The cell membrane is to a considerable extent made up of a double sheet of fatty molecules (the phospholipid bilayer) which is impermeable to most substances. Only small, uncharged molecules such as those of oxygen, carbon dioxide, and water can cross this bilayer.There are apertures in the cell membrane, each of which is formed by one or more protein molecules. These allow across the membrane substances that cannot cross the phospholipid bilayer.The proteins embedded in the phospholipid bilayer are selective. Through such features as channel (pore) size, charge, and three-dimensional shape, these transport proteins (channel and carrier proteins) regulate which substances enter and leave the cell. An important function of the cell membrane is therefore to regulate the passage of atoms, molecules, and ions in and out of the cell. This in turn maintains a stable chemical environment within the cell, which is important, for example, for keeping conditions optimal for intracellular enzymes.Carrier proteins are capable of pumping substances up (against) their concentration gradient, in a process called active transport.The cell membrane has further functions. Protein receptor molecules recognize specific hormones and growth factors, and thus determine whether a cell will respond to a particular signal molecule. And chemical compounds attached to the outside of the cell membrane play a role in adhesion(keeping cells together in a tissue). Furthermore, movements of the cytoskeleton just interior to the cell membrane cause changes to the shape of the membrane, for example in endocytosis and exocytosis.
size/ polarity can be the factors
All cells, whether they are eukaryotic or prokaryotic, have organelles that exist within its cell membrane.
A molecules ability to travel across a cell membrane depends on, among other things; 1. The concentration of the molecule inside and outside of the cell (molecules may travel against the concentration gradient using protein pumps at the cost of ATP). 2. The size of the molecule (large molecules are less likely to pass). 3. The polarity of the molecule (charged molecules have a more difficult time crossing the cell membrane).
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permeabiity
permeability
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permeability
They must either be lipid soluble (e.g. steroids) or very small (e.g. ions).
mass
Lipid solubility determines if it will diffuse across. The presence of specific protein carrier molecules determines if it will be transported across the membrane.
The speed doesn't necessarily determine the permeability, but the size does. Smaller molecules such as O2 can easily enter the cell while CO2 leaves the cell. There are other criteria that also determines whether a molecule can pass through the plasma membrane such as its solubility. Fat soluble molecules such as steroids can easily pass through the membrane.
Whether molecules are able to pass through the membrane depends on the size of the molecules. Smaller ones can, and larger ones cannot. Glucose can pass through a cell membrane because it is a monomer, which is a smaller molecule than the polymer molecules of starch.
One factor is the channel of the molecule, without them the ions and polar molecules would not be able to pass across. Another factor is the size of the molecule, they determine how fast it will defuse.
size and shape. cell membranes are selectively permeable, so only some molecules can get through. (i.e. water can go through, but starch cant) Polarity and size.