copy

Question 1

What is the ester group in cholestrol ester formed between?

Answer 1

carboxylate group of a fatty acid and the hydroxyl group of cholesterol.

Question 2

Why is cholestrol converted into cholestrol ester?

Answer 2

To more efficiently transport both dietary and synthesized cholesterol

Question 3

Why do HDLs change shape from disk shape to a more spherical shape?

Answer 3

Because of the accumulation of cholesterol esters in the HDL which are more hydrophobic leading them to go to the inside of the HDL which causes the spherical shape

Question 4

What is the main dietary source of cholesterol

Answer 4

From chylomicron remnants
Animal products – eggs

Question 5

How much does the body excrete cholesterol per day

Answer 5

Excrete – 1 g/day (bile acids)

Question 6

What are three sources of Cholesterol from extra-hepatic tissues?

Answer 6

Reverse cholesterol transport via HDL
Chylomicron remnants
IDL

Question 7

What does Licthen-cholestrol Acyltransferase (Lcat) do?

Answer 7

Takes a fatty acid from phosphatidylcholine and adds it to Cholestrol which results in it becoming an ester cholestrol.

Question 8

What is the role of Cholestrol ester transfer protein (CETP)?

Answer 8

CETP mediates the transfer of cholesteryl esters from HDL to other lipoproteins, such as low-density lipoproteins (LDL) and very-low-density lipoproteins (VLDL).

Question 9

What molecule is the starting point of cholestrol synthesis and Where in the cell does the synthesis take place?

Answer 9

Starting molecule: Aceytl CoA

Place: Cytoplasm

Question 10

What are the 4 main components that are needed for cholestrol synthesis?

Answer 10

Source of carbon atoms = acetyl CoA from:
ß-oxidation of fatty acids.
Dehydrogenation of pyruvate.
Oxidation of ketogenic amino acids.

Reducing power = NADPH (reduced).
Generated by enzymes in pentose pathway.

ATP energy.

Oxygen