Cell membranes

Question 1

What is phosphatidylcholine?

Answer 1

small molecule choline attached to a phosphate at its hydrophilic head

Question 2

What does amphipathic mean?

Answer 2

Both hydrophilic and hydrophobic qualities

Question 3

How does the arrangement of glycolipids within the phospholipid bilayer differ?

Answer 3

All the glycolipids are in the external monolayer, sphingomyelin is enriched in the external monolayer while phosphatidylinositol, phosphatidylserine and phosphatidylethanolamine are present in the monolayer situated at the interior towards the cytoplasm.

Question 4

How are hydrophilic pockets generated?

Answer 4

particular nature of the side chains of the amino acids lining the pocket

Question 5

What do channels discriminate the ions they transport based on?

Answer 5

their size and on their charge

Question 6

How do transporters work?

Answer 6

Transporters bind selected molecules on one side of the membrane using a specific site. Upon binding, transporters change conformation and they become able to release the compound on the other side of the plasma membrane

Question 7

Why do some transporters have different conformations?

Answer 7

allows a transfer to happen in both directions depending on the direction dictated by the concentration gradient of the solute

Question 8

What is an electrochemical gradient?

Answer 8

A charged solute will then be subjected to two different forces: the concentration and the electrical gradient across the membrane