Questions tagged [membrane-transport]

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Oil absorbed into human skin — where does it go?

For example, I apply petrolatum to my dry hands twice a day as in winter I am usually in a 20-30% RH environment. Within an hour, the petrolatum seems entirely absorbed. According to [1], ...
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60 views

Lipid Diffusion

Epithelial cells in the small intestine absorb lipids through simple diffusion but how does diffusion of lipids occur in the first place if they are insoluble in water? I thought that substances need ...
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59 views

Mobile carriers of Light reaction in higher plants

The hydrogen carrier PQ and the electron carrier PC are the mobile carriers in light reaction facilitating electron transfer from PS II to PS I during non-cyclic process. My question is - How do ...
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209 views

Why difference in degree of folding in a cell?

For a cell to maintain constant volume, input should be equal to output of substances. My question is, if the basolateral membrane, by less folding can attain the same rate of transport as of the ...
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121 views

How do human cells respond to mechanical pressure such as heel contact during walking?

Basically, I'd like to do a full accounting (inventory, assets, liabilities) of a human cell under mechanical pressure. For example, if in steady-state, does the cell consume more or less energy ...
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Nerve/muscle fibre depolarizaitonand repolarization balance

if continously sodium is pumped in during depolarization and pottasium is pumped out during repolarization, eventually there will more sodium and less sodium inside. How the does the fibre/cell return ...
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58 views

Understanding the derivation of the Nernst equation

I am trying to understand how the Nernst equation can be derived and am mostly referring to the explanation given in the book Theoretical Neuroscience by Dayan and Abbott. Given we have a ...
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26 views

How does Ran GDP get from the cytoplasm back to the nucleus following nuclear import and export?

I understand that in Ran-dependent nuclear import Ran GTP binds importin in the nucleus, and after diffusing through the nuclear pore complex Ran GTP is hydrolyzed to Ran GDP and releases importin. ...
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57 views

Exclusion Limit and permeability of outer membrane

According to this textbook: P aeruginosa, for example, which is extremely resistant to antibacterial agents, the outer membrane is 100 times less permeable than that of E coli.[pg.no 27] and then ...
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134 views

Why cells have a membrane potential?

What is the function of the membrane potential? Cells invest huge amounts of ATP to drive ion pumps to sustain this potential. Therefore it must have a very important function. I read somewhere that ...
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44 views

How do (marine) cells not lose potassium?

Eukaryotic cells keep a sodium-potassium gradient across their external membrane. The concentration of potassium ions is about 5mM outside the cell. Although the potential gradient keeps most of these ...
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30 views

Regarding hydrolysis of ATP in ABC transporter

So, I was going through this lecture about ABC transporter and one point about it confused me. ABC transporter is not the same as an ATPase but let's take an example of Cystic Fibrosis Transmembrane ...
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Endocytic pathway: Macropinocytosis

So I'm trying to understand this phrase: Unlike other endocytic pathways, macropinocytosis is acutely induced by growth factors From the following paper The 4 endocytic pathways I know of are ...
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39 views

Are there well studied examples of ERAD-mediated membrane insertion, especially from viruses?

Membrane insertion of transmembrane proteins typically requires highly hydrophobic alpha helixes at the N-terminus, N-terminal signal peptides, tail anchors, or a combination of the three. Byun, H., ...
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354 views

What are internal and external osmotic pressures when referring to a cell?

I've seen the term used but cannot find a clear answer: What are internal and external osmotic pressures when referring to a cell?