Lipid Metabolism: FA Degradation

Question 1

Which FAs can easily pass through the mitochondria and which ones can’t? What is the protocol for the FAs that cannot pass?

Answer 1

SCFAs + MCFAs can pass through

LCFAs can’t ; Protocol–> go to peroxisomes to be broken down into degradable form–> sent to mitochondria for continued Beta-Oxidation

Question 2

What is the general step for FA oxidation?

Answer 2

1. ) FA needs to be broken down by lipases
2. ) FA needs to enter the mitochondria via rate-limiting step of Fatty Acyl-CoA Synthetase
3. ) **Carnitine Acyl Transferase I/ Carnitine Palmitoyl Transferase I will change the CoA–> Carnitine so it can get in through to matrix
4. ) Carnitine Acyl Translocase I will push into the Matrix
5. ) Carnitine Palmitoyl Transferase II/ Carnitine Palmitoyl Transferase II will change the Carnitine–> CoA
6. ) Carnitine will go through the Carnitine Acyl Translocase I back to the intermembrane space

Question 3

Once the FA chain is in the matrix, what are the general steps for the breakdown of one unit of Acetyl CoA?

Answer 3

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

Question 4

What is the net breakdown of 1 Acetyl CoA release?

Answer 4

1 Acetyl CoA
1 NADH–> ETC Complex I
1 FADH2 –> ETC Complex II (CoQ/Ubiquinone)

Question 5

What are the different types of Acyl-CoA dehydrogenase and what does it do?

Answer 5

It catalyzes the first oxidation of the Beta Oxidation in the matrix (Acyl-CoA Dehydrogenase):

Different Types:

• SCAD
• MCAD
• LCAD
• VLCAD

Question 6

What happens during odd-chain oxidation in the mitochondria?

Answer 6

The resulting molecule that becomes produced is Propional-CoA (3-C):

Propionyl-CoA Carboxylase–>
Carboxylates Proionyl CoA (3C)–> Methylmalonyl-CoA (4C)

***A MethylMalonyl-CoA Mutase converts:
Methylmalonyl-CoA–> Succinyl CoA

*Succinyl CoA then falls into the TCA cycle

Question 7

What is the process for unsaturated FAs for degradation?

Answer 7

Reductase followed by Isomerase to get it to Saturated State!

Question 8

What happens when their is defect in MCAD?

Answer 8

Their is a halt in Beta Oxidation which results in the sole use of Glycogen via glucose release

Question 9

What happens when the body starves?

Answer 9

Ketone body from conversion of Acetyl CoA:

1. ) Acetoacetate (23 ATP) (24 -1= 23 for synthesis)
2. ) Hydroxybutyrate (26 ATP)
3. ) Acetyl CoA (24 ATP)

Question 10

What is the bodies process through which the metabolism goes through when the human is not feeding?

Answer 10

1. ) glycogenolysis (few hrs)
2. ) gluconeogenesis (few hrs)
3. ) FA catabolism (Day 1)
4. ) Ketone Body Production + FA catabolism (Day 3)
5. ) Ketone Bodies only (1-2 weeks)