W2-L2: Chemical Energy Derived From Fats & Proteins

Question 1

Stage 1

What is Lipolysis?

Answer 1

Stage 1: Lipolysis

• triglycerides are broken down into glycerol and fatty acids in the mitochondria.
• Glycerol (3-C molecule) – easily converted to pyruvate in liver

Question 2

Stage 2

What happens to the Fatty Acids that are produced from Lipolysis?

Answer 2

Stage 2:
- Fatty acids are linked to coenzyme A
- requires 1 ATP investment
- Results in: Fatty Acyl-CoA

Question 3

Stage 3

What happens to the Fatty Acyl CoA?

Answer 3

Stage 3:
- Fatty Acyl-CoA interacts with carnitine and can cross into mitochondrial matrix (carnitine shuttle)

Question 4

Stage 4:

What is Beta Oxidation?

Answer 4

Stage 4: Beta-oxidation:
- breaks down fatty acids into acetyl-CoA for entry into the Krebs cycle

Question 5

What is the Net Result of Beta Oxidation?

Answer 5

Beta-oxidation
breakdown of fatty acids into acetyl Co-A producing:

• 1 acetylCoA molecule,
• 1 NADH2,
• 1 FADH.

The “snipping off” of the 2-c links will be repeated until only 2-C remain

Question 6

How much ATP is produced through Beta Oxidation?

Answer 6

ATP produced depends on the length of the fatty acid (4 – 26 carbons) – more carbons = more ATP
* E.g. 18c stearic acid = 120 ATP molecules

Question 7

How is Protein used for ATP production?

Answer 7

Proteins are not stored but oxidized to make ATP or converted to new proteins for the growth and repair of the body

Question 8

How do Proteins enter the Krebs Cycle? (4)
Hint: Nitrogen

Answer 8

1. A.A’s stripped of their nitrogen component (deamination)
2. Remaining carbon skeleton can enter the breakdown pathways of the Krebs cycle at many different points
3. Nitrogen component is converted to ammonia and then urea and excreted

Question 9

How much net ATP is produced using Protein?

Answer 9

ATP generated depends on stage AA enters the Krebs cycle – small compared to carbohydrate and fats

Question 10

Summary

Answer 10