, Lipids – Study Notes
Fatty Acids
Definition
Fatty acids are carboxylic acids with long hydrocarbon chains. They can be saturated (no double
bonds) or unsaturated (one or more double bonds).
Synthesis of Fatty Acids
A. Saturated Fatty Acid Synthesis
• Location: Cytoplasm of liver and adipose tissue.
• Precursor: Acetyl-CoA
• Cofactor: NADPH (from Pentose Phosphate Pathway)
• Enzyme: Fatty Acid Synthase (FAS) complex
Steps (Simplified):
1. Activation: Acetyl-CoA → Malonyl-CoA (enzyme: Acetyl-CoA Carboxylase; cofactor: Biotin)
2. Chain elongation: Malonyl-CoA units are added sequentially → Palmitic acid (16:0)
3. Termination: Palmitate is released from FAS
Flowchart – Saturated FA Synthesis:
Acetyl-CoA → [Acetyl-CoA Carboxylase] → Malonyl-CoA → [Fatty Acid Synthase] → Palmitate
(16:0)
Unsaturated Fatty Acid Synthesis
• Location: Endoplasmic reticulum (ER)
• Mechanism: Introduction of double bonds by desaturases
• Humans can form double bonds up to Δ9 position (cannot synthesize omega-3/6)
• Example: Stearic acid (C18:0) → Oleic acid (C18:1, Δ9)
Triacylglycerols (TAGs)
Definition
TAGs are glycerol esters of 3 fatty acids, major storage form of energy.
Fatty Acids
Definition
Fatty acids are carboxylic acids with long hydrocarbon chains. They can be saturated (no double
bonds) or unsaturated (one or more double bonds).
Synthesis of Fatty Acids
A. Saturated Fatty Acid Synthesis
• Location: Cytoplasm of liver and adipose tissue.
• Precursor: Acetyl-CoA
• Cofactor: NADPH (from Pentose Phosphate Pathway)
• Enzyme: Fatty Acid Synthase (FAS) complex
Steps (Simplified):
1. Activation: Acetyl-CoA → Malonyl-CoA (enzyme: Acetyl-CoA Carboxylase; cofactor: Biotin)
2. Chain elongation: Malonyl-CoA units are added sequentially → Palmitic acid (16:0)
3. Termination: Palmitate is released from FAS
Flowchart – Saturated FA Synthesis:
Acetyl-CoA → [Acetyl-CoA Carboxylase] → Malonyl-CoA → [Fatty Acid Synthase] → Palmitate
(16:0)
Unsaturated Fatty Acid Synthesis
• Location: Endoplasmic reticulum (ER)
• Mechanism: Introduction of double bonds by desaturases
• Humans can form double bonds up to Δ9 position (cannot synthesize omega-3/6)
• Example: Stearic acid (C18:0) → Oleic acid (C18:1, Δ9)
Triacylglycerols (TAGs)
Definition
TAGs are glycerol esters of 3 fatty acids, major storage form of energy.
