METABOLISM OF LIPIDS

Beta-oxidation

• metabolic process by which fatty acids are broken down in the mitochondria to generate acetyl-CoA

Ketogenesis

• metabolic process through which the body converts fatty acids into ketone bodies

Fatty Acid Synthesis

• crucial metabolic pathway that converts excess carbohydrates and proteins into fatty acids, which can be stored as fat

Fatty acid activation, transport into mitochondria, beta-oxidation cycle, repeating cycle

Key steps in beta-oxidation

Mitochondria

primary location of beta-oxidation

Beta-oxidation

Purpose: to degrade fatty acids into acetyl-CoA units

1 Acetyl-CoA

• Energy yield from beta-oxidation

• enters citric acid cycle

2.5 ATP

1 NADH produces = ??

1.5 ATP

1 FADH2 produces + ??

Fasting, prolonged exercise, carbohydrate-restricted diets

Ketogenesis - Key energy production during:

Low Carbohydrate diet

• reduced glucose availability prompts the body to switch to fat as its primary fuel source

Exercise

• increased energy demands can trigger ketone production

Fasting

• decreased insulin levels lead to increased fatty acid mobilization

Acetoacetate, Beta-hydroxybutyrate, acetone

Types of Ketone Bodies

Acetoacetate

• first ketone produced

• can be converted into energy

Beta-hydroxybutyrate

• most abundant in the bloodstream

• can cross the blood-brain barrier

Acetone

• Least used for energy

• often execreted

Acetyl-CoA

• the primary building block for fatty acid synthesis

NADPH

• provides the reducing power needed for the synthesis process

Malonyl-CoA

• formed from acetyl-CoA that donates 2-carbon units

Fatty Acid Synthase (FAS)

• the enzyme complex that catalyzes the reaction