Lipids

Question 1

What is the 7 step pathway of lipid digestion and absorption?

Answer 1

1. Bile salts emulsify fat
2. Intestinal lipases degrade
3. Fatty Acid absorption and Triacylglycerols formed
4. Chylomicron formation
5. Lymph circulation
6. LPL in capillaries turn TG into fatty acids and glycerol
7. Oxidation or re-esterfication of fatty acids

Question 2

Describe the process of Glucagon triggering mobilization of stored triacylglycerols.

Answer 2

1. cAMP pathway turning PKA on
2. PKA activates HSL and Perilipin
3. CGI to disassociate from Perilipin.
4. CGI activates ATGL
5. activated HSL and Perilipin reach cell surface
6. Fatty acids and Glycerol are released into blood

Question 3

What does ATGL do? HSL? MGL?

Answer 3

ATGL: Convertes Triacylglycerol into diacyl
HSL: Converts diacylglycerol into mono
MGL: Hydrolyzes monoacylglycerol

Question 4

Insulin inhibits what lipases? Glucagon Activates?

Answer 4

Insulin inhibits ATGL and HL. Glucagon activates it.

Question 5

Glycerol can enter glycolysis how? At the expense of what?

Answer 5

By glycerol kinase activating it, at the expense of ATP

Question 6

What is the first step of transporting fatty acids into the cell? Second?

Answer 6

1. Fatty acid needs to be converted to fatty Acyl-CoA.

2. Transporting via carnitine transporter

Question 7

What inhibits the Acyl-carnitine transferase? What increases this inhibitor?

Answer 7

Malonyl-CoA inhibits. Increased by Insulin.

Question 8

What are the 4 steps of b-oxidation?

Answer 8

1. Dehydration
2. Hydration
3. Dehydration
4. Splitting

Question 9

What enzyme catalyzes the first step of b-oxidation? What does it use? Results in?

Answer 9

Acyl-CoA Dehydrogenase, but using FAD. Results in a trans double bond.

Question 10

What enzyme catalyzes the second step of b-oxidation? What does it use?

Answer 10

Enoyl-CoA Hydratase, adds in H2O

Question 11

What enzyme catalyzes the third step of b-oxidation? What does it use?

Answer 11

b-hydroxyacyl CoA dehydrogenase. Uses NAD

Question 12

What enzyme catalyzes the 4th step of b-oxidation? Results in?

Answer 12

Acyl-CoA Acetyltransferase, splitting off the acetyl-CoA

Question 13

What are the 3 exceptions of b-oxidation?

Answer 13

1. Monosaturated fatty acids
2. Polysaturated fatty acids
3. odd-numbered fatty acids

Question 14

For monosaturated fatty acids, you need what enzyme to b-oxidize it? This does what?

Answer 14

Need isomerase. This turns cis bonds to trans bonds.

Question 15

For poly-saturated fatty acids, you need what enzymes to b-oxidize?

Answer 15

Nedd Isomerase and Reductase (reduces cis bonds).

Question 16

What is the product of turning odd-numbered fatty acids in b-oxidation? this in turn becomes what final product?

Answer 16

Becomes Propionyl-CoA, which becomes Succinyl-CoA