CLS Lipid Metabolism & Physiology 2

Question 1

Which enzyme is responsible for the rate-limiting step in cholesterol biosynthesis?

Accepted Answer

HMG-CoA reductase

Answer

HMG-CoA reductase catalyzes the conversion of HMG-CoA to mevalonate, the committed and rate-limiting step in cholesterol synthesis.

Question 2

In reverse cholesterol transport, which lipoprotein particle delivers cholesterol to the liver for excretion?

Accepted Answer

HDL

Answer

HDL mediates reverse cholesterol transport by accepting free cholesterol from peripheral tissues and delivering it to the liver via SR-BI receptors or by transferring cholesterol esters to apoB-containing lipoproteins.

Question 3

What is the primary function of lipoprotein lipase (LPL) in triglyceride metabolism?

Accepted Answer

Hydrolyzes triglycerides in circulating chylomicrons and VLDL

Answer

LPL is anchored to capillary endothelium and hydrolyzes triglycerides within chylomicrons and VLDL, releasing fatty acids for uptake by muscle and adipose tissue.

Question 4

Familial LPL deficiency typically presents with markedly elevated levels of which lipid fraction?

Accepted Answer

Chylomicrons and triglycerides

Answer

LPL deficiency impairs clearance of chylomicrons, leading to severe hypertriglyceridemia (often >1000 mg/dL) and chylomicronemia syndrome with pancreatitis risk.

Question 5

Which apolipoproteins are associated with HDL particles?

Accepted Answer

ApoA-I and ApoA-II

Answer

HDL particles are primarily characterized by ApoA-I and ApoA-II, which activate LCAT and facilitate cholesterol efflux from macrophages.

(CLS) Clinical Lipid Specialist Certification Practice Test

(CLS) Clinical Lipid Specialist Certification Practice Test

CLS Lipid Metabolism & Physiology 2