2- Cell Membranes

Question 1

What is the function of cholesterol?

Answer 1

decreases permeability

• modulates membrane stiffness
• affects interactions with cytoskeleton

Question 2

What are the 2 types of coupled transporter

Answer 2

Symporters - sugars and amino acids can be dragged into the cell with Na+, as it moves down its concentration gradient
Antiporters - other molecules can move in the opposite direction to Na+ (e.g. H+; Na+-H+ exchanger for intracellular pH regulation)

Question 3

What are common phospholipids?

Answer 3

“phosphatidylethanolamine, phosphatidylserine, phosphatidylcholine (lecithin) and sphingomyelin (ceramide)

Question 4

Describe glucose transport

Answer 4

“Glucose is membrane-impermeant.
Glucose moves down the concentration gradient into the cell
“Glucose binds to a specific glucose transporter which functions by a flip-flop mechanism
The transport is ‘facilitated’ and makes use of the sodium gradient
There are several different glucose transport proteins - some are insulin-sensitive

Question 5

What are the components of phosphatidylcholine?

Answer 5

2 fatty acids, glycerol, phosphate group,, choline

Question 6

What are the components of sphingomyelin?

Answer 6

2 fatty acids, ceramide, phosphate, choline