Lipoprotein Lecture (Lecture 2)

Question 1

Two ways lipids are suspended in blood

Answer 1

(1) transport of fatty acids in association with albumin

(2) components of lipoproteins

Question 2

Features of lipoproteins

Answer 2

(1) surface composed of a monolayer of amphipathic lipids (phospholipids and unesterified cholesterol) and proteins
(2) anhydrous cose, composed of triacylglycerols and cholesterol esters (anhydrous core - containing no water)

Question 3

What are apolipoproteins?

Answer 3

proteins that bind lipids to form lipoproteins; lipid-binding proteins in the blood responsible for the tranport of triacylglycerides, plasma lipids, cholesterol, estified cholesterol

Question 4

What does “Apo” designate?

Answer 4

“Apo” designates the protein in its lipid-free form

Question 5

Purpose of apolipoprotein

Answer 5

(1) act as recognition sites or ligands for receptors
(2) act as structural components
(3) act as activators or coenzymes for enzymes involved in lipid metabollism

Question 6

How do we make distinctions between each lipoprotein?

Answer 6

tissue of origin and average composition

Question 7

Size and density of lipoprotein particles

Answer 7

(1) chylomicrons - lipoprotein particles lowest in density and largest in size, contain the highest percentage of lipid and the lowest percent of protein
(2) VLDLs and LDLs are successively denser, having higher ratios of protein to lipid
(3) HDLs are the densest

Question 8

How are plasma lipoproteis separated

Answer 8

separated on the basis of their electrophoretic mobility or on the basis of their densities by an ultracentrifugation

Question 9

How are apolipoproteins divided

Answer 9

by structure and function into five ajor classes, A through E, with most classes having subclasses

Question 10

What are the 2 basic phases to lipoprotein metabolism?

Answer 10

(1) processing

(2) clearance

Question 11

Processing of lipoprotein

Answer 11

undergo changes in composition of both surface and core components, during transit in the circulation, converting to the remnant form

Question 12

Clearance of lipoprotein

Answer 12

from the blood, via a receptor-mediated endocytotic process

Question 13

Source and function of chylomicrons?

Answer 13

Intestine. Transport of TAG

Question 14

Major apolipoproteins of chylomicrons?

Answer 14

B48, CII, CIII, E

Question 15

Source and function of VLDL?

Answer 15

Liver. Transport of endogenously synthesized TAG

Question 16

Major apolipoproteins of VLDL?

Answer 16

B100, CII, CIII, E

Question 17

Source and function of LDL?

Answer 17

Formed in circulation by partial breakdown of IDL. Delivers cholesterol to peripheral tissues

Question 18

Major apolipoproteins of LDL?

Answer 18

B100

Question 19

Source and function of HDL?

Answer 19

Liver. Removes “used” cholesterol from tissues and takes it to liver

Question 20

Major apolipoproteins of HDL?

Answer 20

AI and AII, CII, CIII, E

Question 21

Pathways for lipoprotein metabolism?

Answer 21

(1) exogenous pathway
(2) endogenous pathway
(3) reverse cholesterol transport pathway

Question 22

Exogenous pathway

Answer 22

chylomicrons, dealing with dietary lipids

Question 23

Endogenous pathway

Answer 23

VLDL, IDL, LDL, dealing largely with de novo synthesized lipids

Question 24

Reverse cholesterol transport pathway

Answer 24

HDL, dealing largely with cholesterol