Lecture 14 - Lipoprotein Metabolism

Question 1

Which is the largest form of lipoprotein?

A. Chylomicron

B. VLDL

C. LDL

D. HDL

Answer 1

A

Question 2

Which lipoprotein has the highest composition of protein?

A. Chylomicron

B. VLDL

C. LDL

D. HDL

Answer 2

D - HDL has slightly more protein content (52%) than lipid content

Question 3

Which has the highest cholesterol and cholesterol ester content comprising its total lipid content?

A. Chylomicron

B. VLDL

C. LDL

D. HDL

Answer 3

C - LDL’s lipid content is 48% cholesterol ester and 10% cholesterol

Question 4

Which two types of lipo proteins have total lipid content that is comprised of more triglyercide than any other type of lipid?

A. Chylomicron/VLDL

B. VLDL/LDL

C. LDL/HDL

D. Only HDL

Answer 4

A - Chylomicron’s lipid content is 88% triglyceride, while VLDL’s lipid content is 56% lipid content.

Question 5

Which type of lipoprotein does NOT contain the B apoprotein?

A. Chylomicron

B. VLDL

C. LDL

D. HDL

Answer 5

D - HDL contains only A, C, and E apoproteins.

Question 6

Which is the smallest and densest lipoprotein?

A. Chylomicron

B. VLDL

C. LDL

D. HDL

Answer 6

D

Question 7

Which lipoprotein contains B-48?

A. Chylomicron

B. VLDL

C. LDL

D. HDL

E. None of these

Answer 7

A

Question 8

Which two apoproteins are ligands for cell surface receptors?

A. Apo A/Apo B

B. Apo A/Apo E

C. Apo B/Apo C

D. Apo B/Apo D

E. Apo B/Apo E

Answer 8

E

Question 9

Which apoprotein acts as a ligand for LDL receptors?

A. Apo A

B. Apo B

C. Apo C

D. Apo E

Answer 9

B

Question 10

Which apoprotein acts as a ligand for remnant receptors?

A. Apo A

B. Apo B

C. Apo C

D. Apo E

Answer 10

D

Question 11

Which apoprotein activates lipoprotein lipase?

A. Apo A

B. Apo B

C. Apo C

D. Apo E

Answer 11

C

Question 12

Which apoprotein is involved in enzyme activation for reverse cholesterol transport?

A. Apo A

B. Apo B

C. Apo C

D. Apo E

Answer 12

A

Question 13

The function of lipoprotein lipase is to hydrolyze triglycerides in chylomicrons/VLDLs to release ______________ and generate remnant lipoproteins.

Answer 13

fatty acids

Question 14

Where is lipoprotein lipase enriched?

A. Adipose tissue

B. Muscle tissue

C. Cardiac tissue

D. Sinusoidal surfaces of liver

E. All of the above except C

F. All of the above except D

Answer 14

F - lipoprotein lipase is enriched in adipose, muscle, and cardiac tissue.

*Note: HEPATIC lipase is localized on sinusoidal surfaces of the liver versus capillaries everywhere.

Question 15

Synthesis of lipoprotein lipase is stimulated by insulin in a specific cell type ONLY. What is this specific cell type?

Answer 15

Adipocytes

Question 16

Both hepatic lipase and lipoprotein lipase hydrolyze ______.

A. Triglycerides

B. Phospholipids

C. Cholesterol

D. Sphingolipids

Answer 16

A

Question 17

Only hepatic lipase hydrolyzes:

A. Triglycerides

B. Phospholipids

C. Cholesterol

D. Sphingolipids

Answer 17

B

Question 18

What are possibilities for the fate of IDLs that are not converted to LDLs by hepatic lipase?

A. Internalized by liver by binding to remnant receptors via Apo E

B. Internalized by liver by binding to remnant receptors via Apo B

C. Internalized by liver by binding to LDL receptors via Apo E

D. Internalized by liver by binding to LDL receptors via Apo B

E. Both A and D

F. Both B and C

Answer 18

E

Question 19

What mediates the transfer of unesterified cholesterol and phospholipids from cell to HDL?

Answer 19

ABCA1

Question 20

Cholesterol in HDL is esterified by:

A. ABCA1

B. LCAT

C. ACAT

D. CETP

E. Scavenger receptor B1

Answer 20

B

Question 21

In the indirect pathway of reverse cholesterol transport, the transport of cholesterol esters from LDL to lipoprotein remnants is mediated by:

A. ABCA1

B. LCAT

C. ACAT

D. CETP

E. Scavenger receptor B1

Answer 21

D

Question 22

In the direct pathway of reverse cholesterol transport, cholesterol esters are directly transferred to tissues from HDL via ____________.

A. ABCA1

B. LCAT

C. ACAT

D. CETP

E. Scavenger receptor B1

Answer 22

E

Question 23

LDL receptors and remnant receptors are btoh involved in the uptake of _____ by the liver.

A. VLDL

B. IDL

C. HDL

D. Triglyerides

Answer 23

B

Question 24

_________ are less localized and more prolific.

A. LDL receptors

B. Remnant receptors

Answer 24

A

Question 25

Which of the following is true when comparing LDL and remnant receptors?

A. Remnant receptors bind Apo B-48, while LDL receptors bind Apo B-100

B. Remnant receptors bind Apo A-I, while LDL receptors bind Apo C-II

C. Remnant receptors bind Apo E, while LDL receptors bind Apo B-100

D. Remnant receptors and LDL receptors both bind Apo B-48

E. Remnant receptors and LDL receptors both bind Apo B-100

Answer 25

C

Question 26

What are the two metabolic fates of IDLs?

Answer 26

1. Taken up by liver (via Apo E –> remnant receptors or via apo B –> LDL receptors)
2. Conversion to LDLs by hepatic lipase

Question 27

A defect in the ABCA1 protein results in?

A. Familial hypercholesterolemia (FH)

B. Hypertriglyceridemia

C. Dybetalipoproteinemia

D. Abetalipoproteinemia

E. Tangier’s diease

F. Fish Eye Disease

Answer 27

E

Question 28

A defect in the enzyme that esterifies cholesterol in HDL causes which disease?

A. Familial hypercholesterolemia (FH)

B. Hypertriglyceridemia

C. Dybetalipoproteinemia

D. Abetalipoproteinemia

E. Tangier’s diease

F. Fish Eye Disease

Answer 28

F - Fish Eye Disease is a defect in LCAT, which esterifies cholesterol in HDL.

Question 29

Which is false regarding LDL receptors and scavenger receptors?

A. Both remove LDL from the plasma

B. Scavenger receptors have alower affinity for LDL than LDL receptors

C. The synthesis of scavenger receptors is NOT regulated by cellular concentrations of choelsterol

D. The synthesis of LDL receptors is NOT regulated by cellular concentrations of cholesterol

E. Scavenger receptors are found on macrophages

Answer 29

D