Fatty Acid Synthesis

Question 1

Site of action of pancreatic lipase? Hormone sensitive? Lipoprotein lipase? Hepatic?

Answer 1

Lumen of digestive tract
Cytoplasm adiposite
Endothelial surface capillaries(by epinephrine)
Hepatocyte surface

Question 2

Process of triglyceride transport and absorption?

Answer 2

Emulsified by bile, digested to fatty acids and 2-acyl glycerol. Reassembled into triglycerides in intestine, transported in lymph as chylomicron

Question 3

How are triglycerides reassembled in the gut?

Answer 3

Convert FFA to CoA and attached to glycerol

Question 4

How are short and medium chain fatty acids transported in blood and through portal?

Answer 4

Attached to serum albumin

Question 5

Where does glycerol come from for triglyceride storage?

Answer 5

From glycerol 3p from DHAP in glycolysis

Question 6

How does insulin affect fat storage?

Answer 6

Stimulates glycolysis and FFA synthesis (via Acetyl CoA Carboxylase). Inhibits fat mobilization (hormone sensitive lipase)

Question 7

What is the rate limiting enzyme in fat synthesis and protein what does it do?

Answer 7

Acetyl CoA Carboxylase. Attaches CO2 to Acetyl CoA with biotin and ATP.

Question 8

Is AMPK a starvation signal?

Answer 8

Yes. Promotes ATP production

Question 9

How is Acetyl CoA Carboxylase regulated?

Answer 9

Inhibited by product palmitoyl CoA, stimulated by citrate. Inactivated by AMPK, stimulated by insulin

Question 10

How does glucagon act on Acetyl CoA Carboxylase?

Answer 10

Uses AMPK to phosphorylate and inactivate it. Indicates fuel mobilization

Question 11

How is initiation of fatty acid synthesis begun?

Answer 11

Acetyl CoA and malonyl CoA attach to fatty acid synthase. Pantothenic acid is cofactor.

Question 12

What is the cofactor for reduction of 3 ketoacyl group on elongating chain?

Answer 12

NADPH

Question 13

Elongation steps of fatty acid synthesis?

Answer 13

ACP binds malonyl CoA, and Acetyl CoA attaches to it. Reduced by NADPH, moved to KA site and repeat.

Question 14

How long is fatty acid chain when thiolase terminates it?

Answer 14

16C

Question 15

How is Acetyl CoA moves from mitochondria to cytoplasm?

Answer 15

Carried on citrate and converted to Acetyl CoA and oxaloacetate

Question 16

How does OAA return to mitochondria?

Answer 16

Changed to malate and transported in. Malate dehydrogenase on both sides, uses NADH

Question 17

What cofactor does malic enzyme use?

Answer 17

NAD+

Question 18

Where does the carbon come from for fatty acids?

Answer 18

Glucose or fructose made into Acetyl CoA

Question 19

What is the product of fatty acid synthase, and how long is it?

Answer 19

Palmitate. 16 c. Can be extended into stearate in ER.

Question 20

How are unsaturated fatty acids made?

Answer 20

Desaturates add double bonds up to 9c limit. Any after is necessary in diet.

Question 21

Desaturation of palmitate produces what? Stearate?

Answer 21

Palmitoleic acid. Oleic acid

Question 22

What is precursor of arachidonate and what is arachidonate?

Answer 22

Linoleic acid. Inflammatory signal

Question 23

How do long chain fatty acids get in blood?

Answer 23

Via the lymph. Travel in chylomicrons. Short and medium go through liver first

Question 24

Where does pancreatic lipase work on triglycerides?

Answer 24

1 and three carbons. Leave one acyl behind to prevent glycerol from fleeing

Question 25

What is the only tissue that can trap glycerol?

Answer 25

Liver (glycerol kinase). Also takes up fatty acyl CoA in blood and produces VLDL to go in blood.

Question 26

Are fat mobilization and gluconeogenesis tied together?

Answer 26

Yes, but fats are never converted to glucose

Question 27

What is acyl-CoA and activated precursor for?

Answer 27

Added to glycerol 3P to make triglycerides

Question 28

Insulin is directly related to F26BP

Answer 28

One is inside cell, one is outside