UNIT2_Lipids & Cholesterol

Question 1

What are the 5 classes of Lipoproteins?

Answer 1

1. Chylomicrons
2. VLDL
3. Remnant particles and Intermediate Density Lipoproteins
4. LDL
5. HDL

Question 2

What are Chylomicrons?

Answer 2

Chylomicrons: made by GI tract from dietary fat.

• 10:1 triglyceride > cholesterol
• Responsible for rise in triglyceride level after meals

Question 3

What are VLDL?

Answer 3

• 5:1 triglyceride > cholesterol
• Made by liver.
• Source of basal triglyceride production.
• Deliver triglyceride to peripheral tissue between meals.
• Decreased production post-meal.

Question 4

What are Remnant particles and Intermediate Density Lipoproteins?

Answer 4

• Metabolic byproducts of metabolism of chylomicrons and VLDL.
• Relatively cholesterol enriched after TG delivered to peripheral tissues (tri=cholesterol).

Question 5

What are LDL?

Answer 5

Low Density Lipoproteins (LDL): produced from metabolism of VLDL.

• Cholesterol > TG → very atherogenic (more dense, smaller, the more atherogenic).
• Cleared from circulation by liver.

Question 6

What are HDL?

Answer 6

High Density Lipoproteins (HDL):

• “Trash trucks” of lipid metabolism
• Collect cholesterol form peripheral tissues and transport it back to liver.
• Reservoir of phospholipids for other lipoprotein particles.
• Can exchange triglyceride and apo-proteins with other particles in circulation.
• Anti-atherogenic

Question 7

What is the majority of lipid in chylomicron?

Answer 7

triglyceride

Question 8

Triglycerides RE-synthesized and packaged into chylomicrons with what?

Answer 8

apoprotein B48

Question 9

List the functions of apo‐lipoproteins and give examples of each.

Answer 9

1) Structural scaffold backbone of lipoprotein particle
ApoB48 → chylomicrons
ApoB100 → VLDL and LDL
ApoA1 → HDL

2) Enzymatic cofactors/regulators
ApoC2 → cofactor for LPL
ApoC3 → inhibits LPL

3) Ligands for receptors
ApoB100 → ligand for LDL receptor
ApoE → ligand for remnant receptor

Question 10

List the relative polarities of cholesterol ester, triglyceride, unesterified cholesterol and phospholipids.

Answer 10

Cholesterol Ester: nonpolar

Triglyceride: nonpolar

Unesterified cholesterol: slightly polar

Phospholipids: slightly polar

Question 11

What is the basic definition/function of Triglycerides?

Answer 11

• Essential source of fuel, stored in tissues or in circulation.
• Energetically dense

Question 12

What is the basic definition/function of Unesterified cholesterol?

Answer 12

• Essential component of cell membranes.
• Precursor for bile salts, steroid hormones, and vitamin D.
• Not metabolized by oxidation, can only be removed from the body by excretion through bile acids.

Question 13

What is the basic definition/function of Phospholipids?

Answer 13

makeup surface of lipoprotein particle.

Question 14

Describe the functions of CETP?

Answer 14

CETP: Allows maturing HDL particle to transfer cholesterol esters to VLDL in exchange for triglycerides.

Question 15

Describe the functions of ABCa1?

Answer 15

ABCa1: ATP binding cassette (ABC) transporter

Important in transport of cholesterol from peripheral tissues to apo A-1 (core apoprotein of HDL)

Question 16

Describe the functions of LCAT?

Answer 16

LCAT: Lecithin cholesterol acyltransferase
Transfers fatty acid from phospholipid onto free cholesterol → esterified cholesterol, that is more nonpolar and more tightly bound to HDL