Lipolysis Flashcards Preview

Biochemistry II > Lipolysis > Flashcards

Flashcards in Lipolysis Deck (31)
Loading flashcards...
1
Q

What hormones stimulate lipolysis?

A

Epinephrine, norepinephrine, glucagon, ACTH, and cortisol

2
Q

What hormones inhibit lipolysis?

A

Insulin

3
Q

The primary control of lipases is through what substance?

A

Hormones

4
Q

Hormone sensitive lipase is strongly inhibited by what?

A

Insulin

5
Q

What lipase is significantly elevated in type 2 diabetes?

A

Adipocyte triglyceride lipase

6
Q

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

A

Hormone sensitive lipase

7
Q

This secondary messenger stimulates lipolysis in fat cells.

A

Cyclic AMP

8
Q

What are the steps of fatty acid degradation?

A
  • 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)
9
Q

How do fatty acids enter the cell to be degraded?

A
  • Albumin binding protein
  • Plasma membrane fatty acid binding protein
  • Fatty acid translocase and fatty acid transport protein
10
Q

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

A

Chaperoned

11
Q

What protein chaperones fatty acids into muscle?

A

Cytoplasmic fatty acid binding protein (FABPc)

12
Q

How is a fatty acid “activated”?

A

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

13
Q

What enzyme “activates” fatty acids?

A

Acyl CoA synthetase

14
Q

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

A

Outer mitochondrial membrane

15
Q

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

A

Pyrophosphate by pyrophosphatase

16
Q

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

A

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

17
Q

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

A

CPT I

18
Q

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

A
  • It is reversibly inhibited by Malonyl-CoA

- Neutral pH is optimum

19
Q

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

A

Beta Oxidation

20
Q

What are the four steps of beta oxidation?

A
  • Oxidation
  • Hydration
  • Oxidation
  • Thiolysis

-OHOT

21
Q

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

A

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

22
Q

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

A

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

23
Q

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

A

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

24
Q

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

A

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

25
Q

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

A
  • 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
26
Q

What additional enzymes are required for unsaturated fatty acid degradation?

A

Reductase and isomerase

27
Q

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?

A

Odd: isomerase
Even: reductase and isomerase

28
Q

Each round of beta oxidation releases what?

A

A two carbon molecule (acetyl CoA)

29
Q

What are key enzymes of fat burning?

A
  • Lipases (Hormone Sensitive Lipase)
  • Acyl CoA synthetase
  • Acyl CoA dehydrogenase
30
Q

What are the inhibitors of fat burning?

A
  • Insulin
  • High energy charge (ATP)
  • NADH and FADH2
31
Q

What are the stimulators of fat burning?

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