8. Lipid Metabolism 2 Flashcards Preview

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Flashcards in 8. Lipid Metabolism 2 Deck (18):
1

Starting with the blood and moving to the cytosol, then the inter membrane space, then the mitochondrial matrix, what are the forms of long chain fatty acids?

  • FA-Albumen
  • (goes through plama membrane)
  • FA-CoA
  • (goes through outer mitochondrial membrane)
  • FA-Carnitine
  • (goes through inner mitochondrial membrane)
  • FA-CoA again
  • (goes through beta-oxidation in the mitochondrial matrix)

2

Long chain fatty acids can be transported via the carnitine shuttle, but VERY long chain fatty acids cannot. Where are VLCFA's changed to LCFA's?

In the peroxisomes, where they are oxidized.

3

What is the rate limiting enzyme in fatty acid degradation?

Carnitine Acyltrasferase 1 (FA-CoA to FA-Carnitine)

4

What are the four main steps in fatty acid degradation? (in order)

  1. Oxidation
  2. Hydration
  3. Oxidation
  4. Thiolysis

5

What enzyme performes the first oxidation in fatty acid degradation?

Acyl CoA Dehydrogenase

6

Which type of acyl-CoA Dehydrogenase is the most common?

MCAD

7

What two enzymes degrade propionyl CoA in odd-numbered FA synthesis?

Propionyl CoA Carboxylase

(Propionyl CoA -> Methylmalonyl CoA)

Methylmalonyl CoA Mutase

(Methylmalonyl CoA -> Succinyl CoA)

8

How do we get energy out of the last three carbons of odd numbered fatty acid degradation?

The propionyl CoA goes to Succinyl CoA and enters into the TCA cycle.

9

What does Trifunctional protien do?

The last three steps of beta-degradation.
 

1- Oxidation (Acyl-CoA Dehydrogenase)

2- Hydration (TFP)

3-Oxidation (TFP)

4-Thiolysis (TFP)

10

What two fancy enzymes do we need to degrade unsaturated fatty acids?

Reductase

(reduces the double bond to clear it)

Isomerase

(moves the disruptive bond)

11

How much ATP is produced in the reduction of a VLCFA to a LCFA?

NONE!

That reaction happens in the peroxisomes where the energy is used to make peroxide.

12

What enzyme initiates peroxisomal beta-oxidation?

Acyl-CoA oxidase

13

What are the main problems with MCAD deficiency?

  • High levels of ammonia
  • Accumulation of C8 fatty acids (poisonous)
  • Dependence on glucose
  • Deficient guconeogenesis due to low pyruvate carboxylase activity.

14

Where are ketone bodies produced?

The liver only - specifically the mitochondrial matrix of hepatocytes.

15

What cell cannot use ketone bodies at all?

Red blood cells

16

During fasting, will the brain be using glucose or ketone bodies? What about peripheral tissues?

The brain uses glucose during fasting.
The peripheral tissues can use ketone bodies during fasting to make sure the brain has glucose. The brain will use ketone bodies as a last resort during starvation.

17

What intermediate between Acetyl CoA and Acetoacetate is essential in the formation of cholesterol?

HMG CoA

18

What are the names of the three ketone bodies?

Acetoacetate (made first, then splits into either...)

Acetone (spontanious reaction, bad breath)

beta-Hydroxybuterate (broken back down to two acetyl CoAs)