41 Answered Questions for the topic Cell Membrane

08/02/19

What is the purpose of co-transport?

My current understanding of co-transport is that, first, a substance is actively transported across a membrane, establishing a concentration gradient across said membrane. This same substance then... more

07/29/19

Can Oxaloacetate cross the outer mitochondrial membrane?

I am aware of the Malate–Aspartate Shuttle, but something is not clear to me and different sources seem to contradict each other. Some show oxaloacetate (OAA) being reduced to malate in the... more

07/25/19

How do detergents get in hydrophobic membrane interior?

According to *Molecular And Cellular Biology* (Stephen L. Wolfe), Membranes disperse almost instantaneously if exposed to a nonpolar environment or to detergents, which are amphipathic molecules... more

07/19/19

How do lipid-soluble substances diffuse through the cell membrane?

It’s said that water-soluble substances can diffuse through cell membrane with less ease than lipid-soluble substances because the former encounters impedance in the hydrophobic region of the... more

07/17/19

Why should phospholipid non-polar tails be "protected" in the membrane bilayer?

>lipids are arranged within the membrane with polar head towards the outer side and non polar tails towards inner side, this ensures that the non polar tail is protected from aqueous... more

07/15/19

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... more

07/10/19

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... more

07/09/19

Membrane Permeability to Pyruvate?

Pyruvate seems to pass easily through the outer membrane of the mitochondrion but has difficulty entering the inner membrane (and gets in by H+ symport). I have two questions: (1) what property of... more

07/08/19

Are all/most/any membranes comprised of lipids from the smooth ER?

I'm attending an introductory high school course to cell biology. Based on my understanding, lipids – the building blocks of membranes – are formed in the smooth ER. Are all/most/any membranes... more

07/04/19

What's inside the perinuclear space?

The cell proper contains the cytoplasm in general and the cytosol in particular when referring to the fluid/gel without notable organelle.Once we move inside the nucleus there is the nucleoplasm... more

07/03/19

Why don't cells of aquatic animals burst?

We know that if we keep plant cells in water, they don't burst because of a cell wall. But the cells of aquatic animals lack cell walls but they still survive. Why?

06/24/19

Why do ribosomes associate with rough endoplasmic reticulum but not other membranes?

As far as I am aware, all eukaryotic membranes consist of a lipid bilayer. Smooth endoplasmic reticulum (ER) and rough ER are distinguished by the presence of ribosome on the rough ER surface, but... more

06/24/19

Why does a "cascade" of events happen during signal transduction?

I've been watching some videos on signal transduction and it says that because there are enzymes being activated by the signal, then there is a "cascade" which happens afterwards...I don't... more

06/21/19

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... more

06/21/19

How to visualize the ECM?

Specifically, I'd like to look at changes in HA (hyaluronic acid) production. Most often you only see people staining the cell surface or removing cells from culture for fixation and then imaging.... more

06/18/19

Can general soap kill bacteria?

I have read that general soap can kill bacteria by opening holes in the bacterial membrane.http://questions.sci-toys.com/node/90However, I found some articles as well saying that it... more

06/15/19

Are Gram negative bacteria classified as such because of their negative membrane potential?

Does the membrane potential usually quoted for Gram negative bacteria (*e.g.*, *E. coli*) refer to the potential across both membranes? - If yes, then does the potential fall more over the inner or... more

06/12/19

Why does a "cascade" of events happen during signal transduction?

I've been watching some videos on signal transduction and it says that because there are enzymes being activated by the signal, then there is a "cascade" which happens afterwards...I don't... more

06/12/19

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... more

06/09/19

Why don't membrane proteins move?

I understand that based on their tertiary structure, intrinsic proteins have hydrophobic non-polar R-groups on their surface and that they 'interact with the hydrophobic core of the cell membrane... more

06/08/19

Are nucleic acids found in cell membranes?

I've found various results online and I was recently marked in on an important test as wrong when I made the assumption they were not found in the cell membrane. Does anyone know what the correct... more

06/08/19

How do detergents get in hydrophobic membrane interior?

According to *Molecular And Cellular Biology* (Stephen L. Wolfe),> Membranes disperse almost instantaneously if exposed to a nonpolar environment or to ***detergents***, which are amphipathic... more

06/03/19

What is a membrane potential?

I know this may be silly, but I am confused to what a membrane potential actually is. I understand that at resting membrane potential is -70- -80 mV. But what does that exactly mean and how does... more

06/02/19

How can a polar molecule pass through polar channels of proteins in the cell membrane?

To transport a polar molecule through the nonpolar cell membrane, a protein with a polar channel is needed to allow it to diffuse. However, if the molecule is polar and the channel is polar,... more

06/01/19

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... more
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