Energy Release from Fat

Flashcards covering the key concepts of energy release from fat, including triglyceride breakdown, fatty acid metabolism, and ketogenesis.

What is the importance of triglyceride fat?

Triglyceride fat is important for long-term fuel storage.

What is the role of adipose tissue lipase?

Adipose tissue lipase breaks down triglyceride into fatty acids and glycerol.

How are fatty acids activated and transported into mitochondria?

Fatty acids are activated to their CoA esters and transported into mitochondria via the carnitine shuttle system.

What products does the β-oxidation pathway yield?

The β-oxidation pathway yields acetyl-CoA, NADH, and FADH2.

What factors regulate fatty acid oxidation?

Factors include lipase enzyme activation, carnitine shuttle rate, and reoxidation of cofactors.

Why can't the liver utilize ketone bodies?

Liver cannot utilize ketone bodies because it lacks the necessary enzymes.

Why can't the brain utilize fatty acids?

Brain cannot utilize fatty acids due to the blood-brain barrier. Uses small amounts of ketone bodies in emergencies.

How are triglycerides stored in the body?

Triglycerides are stored as large fat droplets in the fat cells of adipose tissue.

What is the energy yield (in kJ) per gram of fat, protein, and carbohydrate?

1 g fat yields 38 kJ, 1 g protein yields 21 kJ, 1 g carbohydrate yields 17 kJ.

What is the structure of a triacylglycerol (triglyceride)?

Three fatty acids linked to a glycerol backbone via ester bonds.

How is glycerol metabolized?

Glycerol enters the glycolysis pathway for conversion to pyruvate, then into the TCA cycle, or it can be converted to glucose via gluconeogenesis in the liver.

Where does fatty acid metabolism occur, and in what form are the intermediates present?

Fatty acid metabolism occurs in the mitochondrial matrix, and intermediates are present as CoA thioesters.

Where are long-chain fatty acids activated, and how?

Long-chain fatty acids are activated in the cytosol by the addition of CoA.

How many ATP are required for the activation of fatty acids?

Energetically, activation of fatty acids requires 2 ATP.

Describe the steps of the carnitine shuttle.

Fatty acyl-CoA diffuses across the outer mitochondrial membrane, is converted to fatty acyl-carnitine, crosses the inner membrane via a translocase, and is then reconverted to fatty acyl-CoA.

What are the products of one round of β-oxidation?

One round of β-oxidation produces acetyl-CoA and a fatty acyl-CoA that is 2 carbons shorter.

What happens in Reaction 2 of the 𝛽- oxidation pathway?

Addition of water.

What happens in Reaction 4 of the 𝛽- oxidation pathway?

Removal of 2 C units

What activates the release of fatty acids from adipose tissue?

Adrenaline & glucagon activate lipase enzyme

What are the products of metabolism of odd numbered fatty acids?

β-oxidation will result in C15,C13, C11, C9, C7, C5, and C3.

Excess Acetyl CoA is converted into what in liver?

Acetyl CoA is converted into ketone bodies.

What happens to acetoacetate and β hydroxybutyrate?

Acetoacetate and β hydroxybutyrate are released into the bloodstream.

What energy source do red blood cells use?

Red blood cells cannot utilize fatty acids or ketone bodies and use glucose only.