Lecture 16 - Fatty Acid Synthesis and Storage

Question 1

Fatty acid synthesis is favored by what two molecule types (in excess)?

Answer 1

1. Excess glucose

2. Excess amino acids

Question 2

_____ activates FA synthesis by activating protein phosphatase. This dephosphorylates Acetyl-CoA carboxylase, which activates to convert acetyl-CoA –> malonyl CoA.

Answer 2

Insulin

Question 3

Insulin also stimulates synthesis and storage of _________ by promoting uptake of FA and glucose in adipose tissue.

Answer 3

triglycerides

Question 4

The inner mitochondrial membrane is impermeable to acetyl-CoA, so it is translocated as _________.

Answer 4

citrate

Question 5

What enzyme catalyzes the rate-limiting step in FA synthesis?

Answer 5

Acetyl-CoA carboxylase catalyzes the rate limiting step, converting Acetyl-CoA to malonyl-CoA.

Question 6

Which is an allosteric inhibitor of acetyl-CoA carboxylase?

A. Palmitoyl-CoA
B. Citrate
C. Glucagon
D. Insulin

Answer 6

A

Question 7

Which is an allosteric activator of acetyl-CoA carboxylase?

A. Palmitoyl-CoA
B. Citrate
C. Glucagon
D. Insulin

Answer 7

B

Question 8

Which activates Protein Kinase A (PKA) via cAMP, which in turn phosphorylates and DEACTIVATES acetyl-CoA carboxylase?

A. Palmitoyl-CoA
B. Citrate
C. Glucagon
D. Insulin

Answer 8

C

Question 9

Which activates protein phosphatase, which dephosphorylates and ACTIVATES acetyl-CoA carboxylase?

A. Palmitoyl-CoA
B. Citrate
C. Glucagon
D. Insulin

Answer 9

D

Question 10

The 7 malonyl-CoA requires for FA synthesis are generated from carboxylation of ____________.

Answer 10

acetyl-CoA (by enzyme ACC)

Question 11

The reaction:
acetyl-CoA + OAA –> citrate + CoASH
is catalyzed by _________.

A. Malic DH
B. Malic enzyme
C. Citrate lyase
D. Citrate synthase

Answer 11

D

Question 12

The reaction:
citrate + ATP + CoASH –>
acetyl-CoA + OAA + ADP + Pi
is catalyzed by ________.

A. Malic DH
B. Malic enzyme
C. Citrate lyase
D. Citrate synthase

Answer 12

C

Question 13

Both steps of the pentose phosphate pathway generate _________ to power FA synthesis.

Answer 13

NADPH

Question 14

Which catalyzes the condensation step in FA synthesis?

A. B-ketoacyl-ACP-synthase
B. B-ketoacyl reductase
C. B-hydroxyacyldehydratase
D. enoyl-ACP reductase

Answer 14

A

Question 15

Which catalyzes the dehydration step in FA synthesis?

A. B-ketoacyl-ACP-synthase
B. B-ketoacyl reductase
C. B-hydroxyacyldehydratase
D. enoyl-ACP reductase

Answer 15

C

Question 16

Which catalyzes reduction of the double bond to give a fully saturated FA that is 2 carbons longer?

A. B-ketoacyl-ACP-synthase
B. B-ketoacyl reductase
C. B-hydroxyacyldehydratase
D. enoyl-ACP reductase

Answer 16

D

Question 17

The cofactor for the acyl carrier protein (ACP) in FA synthesis is ____________.

Answer 17

phosphopantetheine

Question 18

What is the function of acyl carrier protein in FA synthesis?

Answer 18

It acts as an anchor for the growing FA chain.

Question 19

The end product of FA synthesis in the liver is _________.

Answer 19

palmitic acid (16:0)

Question 20

The end product of FA synthesis in the lactating mammary gland is ________.

Answer 20

decanoic acid (10:0)

Question 21

What characteristic of the end product of FA synthesis in the lactating mammary gland makes it able to freely diffuse across the intestinal epithelial cells into the portal blood?

Answer 21

it is a C10 - medium chain fatty acid

Question 22

Fatty acids from the liver are delivered to adipose tissue via what two molecules?

Answer 22

1. VLDL

2. Chylomicrons

Question 23

VLDL particles contain what apoprotein that activates the lipoprotein lipase?

A. Apo-B48
B. Apo-B100
C. Apo-CII
D. None of these

Answer 23

C

Question 24

Fatty acid conversion to triglycerides in adipose tissue is activated by the conversion to _________.

Answer 24

fatty acyl-CoA

Question 25

Insulin stimulates both the production of LpL and the entry of glucose into the adipocyte via what glucose transporter? A. GLUT1 B. GLUT2 C. GLUT3 D. GLUT4

Answer 25

D

Question 26

What are 3 functions of phospholipids?

Answer 26

1. Structural component of membranes 2. Enzyme activation 3. Second messenger signaling Note: phospholipids are also important in lung and detergent functioning

Question 27

________ hydrolyzes TAG in the mobilization of fatty acids from triglycerides. A. ATGL B. HSL C. MAG D. All of these

Answer 27

A (triacyltriglycerol lipase)

Question 28

________ hydrolyzes mainly DAG but also TAG in the mobilization of fatty acids from triglycerides. A. ATGL B. HSL C. MAG D. All of these

Answer 28

B

Question 29

________ hydrolyzes MGL in the mobilization of fatty acids from triglycerides. A. ATGL B. HSL C. MAG D. All of these

Answer 29

C

Question 30

Activity in ______ during the mobilization of fatty acids from triglycerides is stimulated by glucagon, epinephrine, and ACTH via phosphorylation and activation. A. ATGL B. HSL C. MAG D. All of these

Answer 30

D (however, mostly HSL is stimulated!)