A selectively-permeable biological membrane that separates the interior of all cells from the outside environment.
A selectively-permeable biological membrane that separates the interior of all cells from the outside environment.
Questions tagged [cell-membrane]
257 questions
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How efficient is the sodium-potassium pump ?
I am reading about transportation of ions in a cell. It is necessary to transport sodium back out and potassium back in, against their electrochemical gradient. This task is carried out by sodium-potassium pump, which transports three sodium ions…
Fatima
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Why does K+ move out of the cell?
I was reading this page: Equilibrium Potentials when I found the following example at the end of the page: "If the K+ equilibrium potential is –90 mV and the membrane potential is –70 mV, in what direction will K+ move through open K+…
Cure
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Why don't all my cell membranes "smush" when I fall?
I've read the question about cell membranes breaking apart, which is close to what I'm asking, though I'm trying to probe a bit deeper.
I understand that there are hydrophobic forces keeping the cell membrane together, and I'm roughly picturing the…
Justin
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Is Active Transport Required For Life?
Is active transport required for all living cells to function?
I was under the impression that if a cell doesn't have active transport, it either would lose molecules through the membrane and not be able to maintain a proper gradient, or molecules…
John
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Why don't surfactants destroy or incorporate into cell membranes?
How do surfactants remain on the surface of pneumocytes without (1) acting as a detergent or (2) the phospholipids getting incorporated into the membranes of pneumocytes...
I'm guessing the answer has something to with the secretions of clara…
Jasand Pruski
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Why does K+ have more concentration inside of the cell compared to outside of the cell? Why is Na+ and Cl- the opposite?
Can someone tell me the fundamental reason why K+ has low concentration outside of the cell and more inside of the cell?
Project Backlog
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How is the cell membrane protective?
Generally in biology books, it is written that the cell membrane is selectively permeable and that it has a protective function, as in here
It says that the cell membrane protects the cell from its surroundings. However the selective permeability is…
pjmathematician
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Is the reason why lipid-soluble molecules can pass through membrane because
I have been studying about cell membranes and how water molecules are able to pass through it. (https://www.wiley.com/college/boyer/0470003790/animations/membrane_transport/membrane_transport.htm)
It is clear that the water molecules can squeeze…
Christopher U
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Visibility of a cell membrane under microscopic Imaging
When we see any cell under a microscope the membrane surrounding the cell is opaque. But then if the cell membrane surrounds the cell in all the three dimensions how come we can see through the cell membrane and have a look at the organelles inside…
hesk
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Effect of extracellular molecules on membrane potential
I am reading about the effect of extracellular potassium and chloride on the membrane potential, and now a question has come to my mind about what would happen if we added some molecules that have no charge to the extracellular? (consider that only…
Fatima
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How does soap affect membrane permeability? Which component of the membrane does it affect?
In a lab we used distilled water + 3 drops of soap to examine how beetroot would be affected by it. I believe the beetroots membrane denatured and a red pigment leaked from it. However, I cannot explain why this has happened. Can anyone explain the…
DoubleHelix
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Ion Channel gating
I have been studying ion channels and there is one thing i am confused about, gating between open and closed states in channels.
Am i right in thinking gating is so fast that it is effectively always open for ion flow? So that if ten ions flow…
user3261646
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Why doesn't the polar side of the plasma membrane block nonpolar diffusion?
It is often stated that small molecules or nonpolar molecules can diffuse through the plasma membrane because they can pass through the middle nonpolar bit, but why don't the polar sides block these nonpolar molecules. Estrogen is nonpolar and can…
Robotic_Cow
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Why is a membrane polar on the outside and non-polar in the inside?
Why would the phospholipid bilayer want to be polar on the outside and non-polar in the inside? why would it not want to be the opposite?
user34748
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