Lipids 2

Question 1

Describe the release of fatty acids from triacylglycerol in adipocytes

Answer 1

Hormone sensitive lipase activates protein kinases (adds phosphate to TAG-lipase) which digest TAG to DAG and then other lipase work to digest it further to free fatty acids

Question 2

How does B-Oxidation digest fatty acids?

Answer 2

Two carbon residues at a time

Question 3

What is the useful product(s) of B-Oxidation used in the CAC?

Answer 3

Acetyl CoA, NADH and FADH2

Question 4

How many stages does B-Oxidation occur in?

Answer 4

Three

Question 5

What is the first stage of B-Oxidation?

Answer 5

Activation of fatty acids in the cytosol (adding a Co-A group)

Question 6

What is the second stage of B-Oxidation?

Answer 6

Transportation into the mitochondrial matrix through the carnitine shuttle

Question 7

Describe the carnitine shuttle?

Answer 7

1. Fatty acid-CoA diffuses over first mitochondrial matrix
2. Fatty-acid binds to carnitine (CAT-I) and moves through the second membrane
3. CAT-II enzyme reforms fatty acid-CoA

Question 8

What is carnitine made of?

Answer 8

From dietary lysine and methionine

Question 9

What is the third stage of B-Oxidation?

Answer 9

Degradation of two carbon fragments as acetyl-CoA

Question 10

Describe the third stage of B-Oxidation as four steps

Answer 10

1. Dehydrogenation (oxidation producing FADH2)
2. Hydration
3. Dehydrogenation (oxidation produces NADH)
4. Thiolysis - produces Acetyl-CoA

Question 11

What role does the peroxisome play in B-Oxidation?

Answer 11

Very long fatty acid chains (>22) undergo preliminary oxidation in the peroxisome

Question 12

Why can’t animal convert fatty acids to glucose?

Answer 12

Thermodynamically unfavourable