Lipid Anabolism

What is the primary function of Triacylglycerols (Triglycerides)?

Energy storage in adipose tissue.

Which enzyme regulates fatty acid synthesis and determines if acetyl-CoA is used for lipids or enters the TCA cycle?

Acetyl-CoA Carboxylase.

What is the direct carbon source for every carbon atom in a cholesterol molecule?

Acetyl-CoA.

In which cellular compartment does fatty acid synthesis occur?

The cytosol.

What must happen to Acetyl-CoA in the mitochondria before it can be used for fatty acid synthesis in the cytosol?

It condenses with oxaloacetate to form citrate

What is the primary building block molecule added to the growing fatty acid chain during synthesis?

Malonyl-CoA.

How is Malonyl-CoA formed?

Acetyl-CoA Carboxylase converts Acetyl-CoA to Malonyl-CoA by adding bicarbonate. This reaction costs 1 ATP.

What is the role of Acyl Carrier Protein (ACP) in fatty acid synthesis?

It acts as the central anchor/scaffold on the Fatty Acid Synthase complex where the growing fatty acid chain is built.

What type of reducing equivalent is required by the reductase enzymes during fatty acid synthesis?

NADPH.

How many ATP equivalents (ATP + NADPH) are invested to synthesize one molecule of Palmitate (16-carbon fatty acid)?

42 ATP equivalents (7 ATP for malonyl-CoA formation + 14 NADPH used for reductions

Which type of tissue stores lipids for energy under the skin?

Subcutaneous adipose tissue.

What two precursor molecules are required to synthesize a Triacylglycerol?

A glycerol backbone (Glycerol 3-phosphate from glycolysis or lipolysis) and Fatty Acyl-CoAs.