Cell Membrane (LE002)

Question 1

What molecules can readily diffuse across the membrane?

Answer 1

Gases (O2, CO2, NO)
Steroids (hydrophobic)
Water

Question 2

What comprises the hydrophilic head group of a phospholipid?

Answer 2

Choline + Phosphate + Glycerol

The choline part could be varied, to recruit different types of proteins to the cell membrane.

Question 3

How do saturated / unsaturated hydrocarbon chains of a phospholipid affect the membrane fluidity at physiological temperature?

Answer 3

If no unsaturated (no kinks), then would be solid at physiological temperature
Need unsaturated to keep it fluid.

Question 4

What is a GPI protein?

Answer 4

They are proteins that are covalently bonded to a phospholipid on the outer leaflet of the bilayer membrane.

Question 5

T/F: Receptors are not integral proteins.

Answer 5

False.

All receptors have both an external and internal domain, and are integral proteins.

Question 6

What is the significance of intracellular Calcium concentration?

Answer 6

There is 1/10 of a micromolar of Ca2+ intracellularly. A lot of cellular activity are calcium dependent so it must be kept low so that increases can be used to modulate / stimulate various pathways. When Ca2+ increases cystolically, will lead to cell death.

Question 7

How does cytoskeleton provide structural support for plasma membrane? What happens in muscular dystrophy?

Answer 7

The cytoskeleton will create a meshwork along with interact with integral membranes. In muscular dystrophy, the protein that allows cytoskeleton to interact with the membrane is not there, so there is minimal structural support.