Lipolysis

Question 1

What hormones stimulate lipolysis?

Answer 1

Epinephrine, norepinephrine, glucagon, ACTH, and cortisol

Question 2

What hormones inhibit lipolysis?

Answer 2

Insulin

Question 3

The primary control of lipases is through what substance?

Answer 3

Hormones

Question 4

Hormone sensitive lipase is strongly inhibited by what?

Answer 4

Insulin

Question 5

What lipase is significantly elevated in type 2 diabetes?

Answer 5

Adipocyte triglyceride lipase

Question 6

The skeletal muscle protein content of this lipase is significantly reduced in type 2 diabetes.

Answer 6

Hormone sensitive lipase

Question 7

This secondary messenger stimulates lipolysis in fat cells.

Answer 7

Cyclic AMP

Question 8

What are the steps of fatty acid degradation?

Answer 8

• Enters the muscle
• Fatty acid is activated by being converted into acyl CoA
• Fatty acid enters the mitochondria
• Fatty acid is oxidized in the mitochondria (oxidation, hydration, oxidation, and thiolysis)

Question 9

How do fatty acids enter the cell to be degraded?

Answer 9

• Albumin binding protein
• Plasma membrane fatty acid binding protein
• Fatty acid translocase and fatty acid transport protein

Question 10

Any fatty acid entering the muscle to be oxidized, must be ____ by a protein.

Answer 10

Chaperoned

Question 11

What protein chaperones fatty acids into muscle?

Answer 11

Cytoplasmic fatty acid binding protein (FABPc)

Question 12

How is a fatty acid “activated”?

Answer 12

By attaching coenzyme A to the fatty acid to create acyl CoA

Question 13

What enzyme “activates” fatty acids?

Answer 13

Acyl CoA synthetase

Question 14

Where does the “activation” of fatty acids take place?

Answer 14

Outer mitochondrial membrane

Question 15

Hydrolysis of this substance is common in biosynthesis and makes the activation of fatty acids irreversible.

Answer 15

Pyrophosphate by pyrophosphatase

Question 16

What is responsible for the transport of long chain fatty acids into the mitochondria?

Answer 16

Carnitine Palmitoyltransferase Complex (consists of CPT I, acylcarnitine translocase, and CPT II)

Question 17

For entering the mitochondria what is considered the rate limiting step?

Answer 17

CPT I

Question 18

What inhibits fatty acid entrance into the mitochondria? What is the optimum pH for entrance into the mitochondria?

Answer 18

• It is reversibly inhibited by Malonyl-CoA

- Neutral pH is optimum

Question 19

This term refers to the four steps that occur prior to having fat enter the aerobic system.

Answer 19

Beta Oxidation

Question 20

What are the four steps of beta oxidation?

Answer 20

• Oxidation
• Hydration
• Oxidation
• Thiolysis

-OHOT

Question 21

During beta oxidation, what occurs in the first step of oxidation?

Answer 21

Acyl CoA is converted into trans-Δ^2-enoyl CoA by acyl CoA dehydrogenase

Question 22

During beta oxidation, what occurs in the second step of hydration?

Answer 22

Trans-Δ^2-enoyl CoA is converted into L-3-hydroxyacyl CoA by enoyl CoA hydratase

Question 23

During beta oxidation, what occurs in the third step of oxidation?

Answer 23

3-hydroxyacyl CoA is converted into 3-Ketoacyl CoA by L-3-hydroxyacyl CoA dehydrogenase

Question 24

During beta oxidation, what occurs in the fourth step of thiolysis?

Answer 24

3-ketoacyl CoA is converted into Acyl CoA (minus “2”) and acetyl CoA by beta-ketothiolase

Question 25

What are the similarities of beta oxidation to the Kreb's cycle?

Answer 25

- Oxidation produces a double bond and FADH2 via dehydrogenase - The addition of water adds a hydroxyl group and removes a double bond - Oxidation turns the hydroxyl group into a carbonyl group via dehydrogenase

Question 26

What additional enzymes are required for unsaturated fatty acid degradation?

Answer 26

Reductase and isomerase

Question 27

Polyunsaturated fatty acids require only one or two extra enzymes depending on the number of double bonds. Which enzymes are needed for odd numbered? Even numbered?

Answer 27

Odd: isomerase Even: reductase and isomerase

Question 28

Each round of beta oxidation releases what?

Answer 28

A two carbon molecule (acetyl CoA)

Question 29

What are key enzymes of fat burning?

Answer 29

- Lipases (Hormone Sensitive Lipase) - Acyl CoA synthetase - Acyl CoA dehydrogenase

Question 30

What are the inhibitors of fat burning?

Answer 30

- Insulin - High energy charge (ATP) - NADH and FADH2

Question 31

What are the stimulators of fat burning?

Answer 31

- Glucagon - Low energy charge (ADP or AMP) - NAD+ and FAD