Lecture 27: Fatty acid oxidation

Question 1

How are fatty acids delivered to the mitochondria for oxidation?

Answer 1

After the activation process, the acyl-CoA is transferred through the mitochondria membrane into the mitochondrial matrix

• Fatty acyl CoA passively passes through a fatty acyl-CoA carrier protein and into the inter membrane space
• It then undergoes a reaction to become fatty acyl-carnitine which allows it to cross the inner membrane and into the matrix via a carnitine protein
• fatty acyl-carnitine then undergoes a reaction to become fatty acyl-CoA
• B-oxidaiton then can take place in the matrix

Question 2

Why are fatty acids used as fuel ?

Answer 2

• Fat is the primary energy reserve
• Fats are lighter to store
• Fats are more reduced than carbohydrates (stored carbs are approximately 2/3 water)

Question 3

What is fatty acid activation?

Answer 3

The attachment of fatty acids to coenzyme A is called fatty acid activation

• occurs in cytoplasm
• fatty acid activation occurs before the fatty acid enters the mitochondria
• energy from hydrolysis of ATP
• catalysed by the enzyme Acyl-CoA synthetase

Question 4

Describe the process of the catabolism of fat reserves - include fatty acid activation

Answer 4

When body fat reserves are needed for fuel, fatty acids are released into the blood. Free fatty acids bind albumin and are released to all peripheral tissues - pass through cell membrane and into the cytoplasm.
- In the cytoplasm fatty acids are attached to coenzyme A. Fatty acids begin catabolism via B-oxidation. The attachment of fatty acids to coenzyme A is called fatty acid activation, and this occurs before the oxidation process that occurs in the mitochondria

Question 5

What is B-oxidaiton ?

Answer 5

B oxidation uses fatty acid with an even number of carbons that are saturated

• No ATP is made
• the energy released in B oxidant is transferred to the coenzymes NAD+ and FAD+ which become NADH and FADH2 - hydrogens are removed from fatty and are transferred to the coenzymes
• the end products acetyl-CoA which is further oxidised in the CAC and the coenzymes which are used in the electron transport chain to allow the generation of ATP by oxidative phosphorylation.

Question 6

Describe the B-oxidation process?

Answer 6

• Oxidation process involves a series of cyclic reactions. Long chain fatty acids which an even number are shortened by the removal of 2 carbon units
  Fatty acyl-CoA ——–> Acetyl-CoA
• Each cycle consists of four reactions occurring at the carboxyl end of the fatty acid