Complex Lipids Study Guide

These flashcards cover key concepts on complex lipids, including phospholipid types, synthesis pathways, cholesterol metabolism, steroid hormones, and lipoprotein functions.

What are the two main types of phospholipids?

Glycerophospholipids and sphingolipids.

What is the common precursor for triglyceride and phospholipid synthesis?

Phosphatidic acid and diacylglycerol (DAG).

Which enzyme activates choline to form phosphatidylcholine?

Pyrophosphorylase (forms CDP-choline).

What is the key phospholipid of the inner mitochondrial membrane?

Cardiolipin (diphosphatidylglycerol).

How do sphingolipids differ from phospholipids?

Sphingolipids have a sphingosine backbone and an amide linkage; phospholipids have glycerol and ester linkages.

Which sugar determines blood type A?

N-acetylgalactosamine.

Which enzyme catalyzes the rate-limiting step in cholesterol synthesis?

HMG-CoA reductase.

What is the mechanism of statins?

Inhibit HMG-CoA reductase → lower intracellular cholesterol → increase LDL receptor expression.

What are the main functions of bile acids?

Emulsify fats, aid digestion, and facilitate lipid absorption.

What enzyme controls bile acid synthesis?

7α-hydroxylase (CYP7A1).

What are the three classes of steroid hormones?

Corticosteroids, androgens, and estrogens.

Which lipoprotein carries cholesterol to tissues?

LDL.

Which lipoprotein removes cholesterol from tissues?

HDL.

What receptor mediates LDL uptake?

LDL (ApoB/E) receptor.

How do scavenger receptors differ from LDL receptors?

Scavenger receptors are unregulated and can cause cholesterol overload.

In the fed state, which lipoproteins dominate transport?

Chylomicrons.

In the fasting state, which lipoproteins dominate?

VLDL and LDL.

What is the purpose of the overflow pathway?

Handle excess cholesterol by LDL transport and scavenger receptor uptake.

What is the main marker used to measure lipid transport activity in clinical settings?

Plasma triglycerides.

What are the main organs responsible for steroid hormone synthesis?

Adrenal cortex, testes, and ovaries.

How are steroid hormones excreted?

Reduced, conjugated to polar molecules, and excreted in urine.