Lipids and Lipoproteins

Question 1

How many acetyl CoA are used to generate one isopentenyl pyrophosphate (IPP)?

Answer 1

Three

Question 2

IPP serves as a building block for synthesis of all?

Answer 2

Isoprenoids

Question 3

Where is acetyl CoA generated in?

Answer 3

Mitochondria

Question 4

What are sources of acetyl CoA?

Answer 4

1) Pyruvate
2) FA
3) AA

Question 5

Acetyl CoA is transported into cytoplasm via?

Answer 5

Citrate shuttle

Question 6

How many units of IPP form tetracyclic sterane ring?

What is it the backbone of?

Answer 6

1) Six

2) Steroids

Question 7

Alicyclic compound is made of of?

Answer 7

Four fused sterane rings

Question 8

Cholesterol has one hydroxyl group at?

Answer 8

C3

Question 9

Excess cholesterol may lead to?

Answer 9

Atherosclerosis

Question 10

How many acetyl CoA, ATP, and NADPH is involved in the synthesis of one cholesterol?

Answer 10

1) 18 Acetyl Coa
2) 18 ATP
3) 16 NADPH

Question 11

What is the rate limiting step in cholesterol biosynthesis?

Answer 11

HMG-CoA reductase

Question 12

What is an inhibitor of HMG CoA Reductase?

Answer 12

Statins (cholesterol lowering drugs)

Question 13

What type of inhibitor are statins?

Answer 13

Competitive inhibitors

Question 14

What is the Km for HMG CoA?

What is the Ki for statins?

Answer 14

1) 4 um

2) 5-45 nM

Question 15

The increase in Sterol Regulatory Element BInding Protein (SREBP) maturation leads to?

Answer 15

Transcription of LDL receptor and clearance of cholesterol via endocytosis

Question 16

What is the myotoxic side effect of statins?

Answer 16

Depletion of muscle levels of ubiquinone (CoQ10)

Question 17

One fate of cholesterol is it can be converted to cholesterol esters by?
Another fate is it can be packaged into?

Answer 17

1) ACAT (Acyl CoA: cholesterol acyltransferase)

2) VLDL and released into blood

Question 18

How does insulin affect HMG CoA Reductase?

How does glucagon affect HMG CoA Reductase?

Answer 18

1) Activates

2) Inactivates

Question 19

Which lipoprotein has the most TAGs and least protein?
Which has the least TAGs and most protein?
Which is made in liver and is packaged with TAGs and cholesterol?
Which is considered bad cholesterol?

Answer 19

1) Chylomicrons
2) HDL
3) VLDL
4) LDL

Question 20

What is the major carrier of cholesterol in blood to peripheral tissues?
What is its role when it reaches the peripheral tissue?

Answer 20

1) LDL

2) Regulate synthesis of cholesterol at these sites

Question 21

HDL is crucial for maturation of?

Answer 21

Chylomicrons

Question 22

What is reverse cholesterol transport?

Answer 22

HDL retrieves cholesterol such as LDL-cholesterol from other tissues in the body to return the cholesterol to the liver for excretion as bile

Question 23

What is a cholesterol transport protein in endothelial cells and macrophages?
Loss of the protein activity results in a rare condition called?

Answer 23

1) ABCA1

2) Tangier disease

Question 24

Which lipoprotein has antioxidant and anti-inflammatory properties?

Answer 24

HDL

Question 25

HDL-C levels are increased by?

Answer 25

Weight loss and exercise

Question 26

What is Type I hyperchylomicronemia caused by? What does this lead to? Clinical symptoms? Treatment?

Answer 26

1) Deficiency in apoC-II or LPL 2) Chylomicrons and TAGS increase 3) Xanthomas 4) Low fat diet

Question 27

What is Xanthomas?

Answer 27

Nodules of cholesterol in skin/tendons

Question 28

What is Type II hyperchylomicronemia caused by? What does this lead to? Clinical symptoms? Treatment?

Answer 28

1) Defects in LDL receptor 2) Increase in cholesterol and LDL 3) Xanthomas 4) Diet, statins, LDL apheresis or liver transplant

Question 29

The accumulation of what lipoprotein under the endothelial cells lining blood vessels is positively correlated with cardiovascular disease?

Answer 29

LDL

Question 30

What creates arterial plaques which ultimately lead to atherosclerosis?

Answer 30

Oxidized LDL --> macrophages --> foam cells

Question 31

With type I hyperchylomicronemia, primary LPL deficiency manifests in? APO C-II deficiency manifests?

Answer 31

1) Infancy | 2) Post adolescence

Question 32

ApoB100 is found on which lipoprotein?

Answer 32

LDL

Question 33

ApoA-1, ApoE, and ApoC-II are found on which lipoprotein?

Answer 33

HDL

Question 34

What activates capillary lipoprotein lipase? What is resposible for hepatic endocytosis of VLDL? What activates an enzyme that turns cholesterol into cholesterol ester?

Answer 34

1) ApoC-II 2) ApoE 3) ApoA-I