Lipid Metabolism

Question 1

what is a triglyceride?

Question 2

describe what happens to adipose tissues during fasting stage (glucagon level high).

Answer 2

adipocytes is broken down into glycerol and fatty acids, they get into blood and undergoes glycolysis and tissues (SK muscles, heart muscle, kidney, liver -> oxidation occurs in mitochondrial matrix -> oxidised for energy).

Question 3

How do we make ATP from fats?

Answer 3

all roads leads to Acetyl CoA
TAGs -> Fatty acids -> Acetyl Co A -> TCA cycle -> Electron Transport Chain -> ATP

Question 4

Fatty acid beta oxidation

Answer 4

1. chopping fatty acids by removing two carbon units each time.
2. each two carbon unit is Acetyl Co A.
3. Chopping involves the reduction of NAD and FAD.
4. First step invovles uptake of fatty acids into mitochondrial matrix.

Activation: ATP + Fatty acid + Co A -> Fatty acyl CoA + Carnitine (shuttle protein).

Question 5

What happens within the mitochrondial matrix?

Answer 5

stage 1:
beta oxidation -> 8-acetyl-CoA
NADH, FADH2

Stage 2:
8-acetyl-CoA -> citric cycle -> 64e- -> NADH, FADH2

Stage 3:
Respiratory (electron transfer) chain converting ADP into ATP.
Produces Water as a by-product.

Question 5

Ketones for energy

Answer 5

Normal response to lower CHO (starvation)

Excess production -> diabetes and ketoacidosis.

Question 6

Ketones made in the liver during starvation

Answer 6

Question 7

How is fatty acid oxidation facilitated?

Answer 7

Question 8

How is Fatty Acid Synthesised?

Answer 8

Insulin activates fatty acids synthesis - well fed state.
1. Process is initaited by transport of citrate out of the mitochondria.
2. Citrate in the cytoplasm is converted to acetyl CoA.
3. Fatty acids is build as 2 carbon units at a time in the cytoplasm of liver.
4. The process stops at palmitate.

Question 9

How is fatty acid synthesis regulated?

Answer 9

Incativators involves glucagon and epinephrine - for fight or flight response.

Activators has citrate - TCA intermediate transported out of mitochrondria. Fat is made when citrate is high. -> blocks beta oxidation by stopping transport of fatty acids across the mitrochondrial membrane. Makes fat (in cytoplasm) instead.
Insulin - not produced in diabetes type 1.

Question 10

Give an overview of starvation process in liver cells.

Answer 10

Question 11

Give an overview of well-fed state process in liver cells.

Answer 11