A selectively-permeable biological membrane that separates the interior of all cells from the outside environment.
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1answer
23 views
Diffusion Question (in cell membrane)
I got this question and don't really understand the difference between the answers.
Diffusion is (in cell membrane):
a) passive by nature, no metabolic energy is needed
b) driven process by ...
2
votes
1answer
30 views
Will lipid molecules 'flip-flop' over a membrane without the use of an enzyme?
All of the references to this I can find refer to enzymes like Flippase making it 'easier' or 'more likely' that the translocation will occur, rather than actually make it possible.
The following is ...
4
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1answer
130 views
Efficiency of a 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 ...
3
votes
1answer
36 views
What molecular processes are involved in pseudopodial extension?
I am curious as to the processes and mechanisms involved in the extension of pseudopodia in amoeba. How does the cell know and control the direction and extent of pseudopodia formation at a molecular ...
5
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1answer
95 views
Can in the case of multiple sclerosis (MS), a too high osmotic pressure in the nerve, lead to a high intracellular concentration of potassium?
Can in the case of multiple sclerosis (MS),
a too high osmotic pressure in the nerve,
lead to a high intracellular concentration of potassium,
and also lead to 'pumping up' of nerve cells,
which then ...
3
votes
2answers
210 views
Simple diffusion of lipid-soluble molecules through phospholipid bilayer — does anything get “stuck” in transit?
It's a pretty elementary concept, and when I first learned of it I don't think I had the foundations to even think of such a question, but I found myself the other day thinking about the amphipathic ...
4
votes
2answers
95 views
Question about equilibrium potential formula
My biology book says, that the equilibrium potential for an ion with a charge of +1 is: $$E_{ion}= 62mV \biggl(\log\frac{[ion]_{outside}}{[ion]_{inside}}\biggr)$$
Where does the 62 mV come from? How ...
4
votes
1answer
80 views
How are lysosome membranes protected from the attack of hydrolases?
Lysosomes are a bit like the suicidal bags of cells. They help to clean cells, have an acidic pH and contain a large number of hydrolyzing enzymes.
But why don't these hydrolyzing enzymes attack ...
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0answers
35 views
The relationship between the currents of intracellular and extracellular ions of a cell
In a cell, assume that only sodium, potassium, chloride and calcium ions can cross the membrane and their currents are: $I_{Na}$, $I_{K}$, $I_{Cl}$ and $I_{Ca}$, across the whole membrane. There is ...
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vote
2answers
101 views
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 ...
4
votes
1answer
114 views
If proteins have an overall charge, how do membrane proteins traverse through the hydrophobic region of the plasma membrane?
These two concepts seem almost contradictory, proteins have a net negative charge due to the amino acids in them each having a small negative charge, yet membrane proteins are able to exist traversing ...
5
votes
1answer
165 views
Why do grapes not shrink when placed in strong sugar solution?
I tried an experiment. First, I placed grapes in pure water(hypotonic solution). The grapes burst because of endosmosis. Then, I placed new set of grapes in strong sugar solution(fully saturated) but ...
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votes
1answer
30 views
Could silicon oil block Na+ ion channels in the membrane of an axon and prevent Na+ influx?
Could silicon oil block Na+ ion channels in the membrane of an axon and prevent Na+ influx?
I have been wondering if Na+ influx could have been a diluting factor in anterograde fills. If so, could ...
5
votes
2answers
398 views
Are cells really the basic unit of all life? [closed]
Please see comments as to the appropriateness of this question on biology SE.
All known life on Earth is made up of cells. It is thus safe to say that all known life is characterized by the presence ...
7
votes
1answer
88 views
What specific membrane adaptations do cells have for saline-rich environs?
Are the cells of marine animals and flora equipped with special ion exchange pumps to mitigate the effects of a saline-rich environment?
Or have the cell's membranes adapted through structural ...
