Q: Which of the following is the correct equation for the overall degradation of palmitoyl-CoA via β-oxidation?

$$\text{Palmitoyl-CoA} + 7 \text{CoA-SH} + 7 \text{FAD} + 7 \text{NAD}^+ + 7 \text{H}_2\text{O} \rightarrow 8 \text{acetyl-CoA} + 7 \text{FADH}_2 + 7 \text{NADH} + 7 \text{H}^+$$

Q: Which equation correctly represents the net reaction for palmitate biosynthesis from acetyl-CoA?

$$8 \text{Acetyl-CoA} + 7 \text{ATP} + 14 \text{NADPH} + 7 \text{H}^+ \rightarrow \text{palmitate} + 14 \text{NADP}^+ + 8 \text{CoA-SH} + 7 \text{ADP} + 7 \text{P}_i + 6 \text{H}_2\text{O}$$

Question 1

Which property of triacylglycerols (TAGs) makes them the most efficient energy storage molecule in humans?

Accepted Answer

They are highly reduced, yielding more energy per gram than carbohydrates or proteins.

Question 2

Why does the hydrophobic nature of TAGs contribute to their role as energy storage molecules?

Accepted Answer

It enables TAGs to be stored without associated water, minimizing weight and maximizing energy density.

Question 3

Which of the following is the correct equation for the overall degradation of palmitoyl-CoA via β-oxidation?

Accepted Answer

$$	ext{Palmitoyl-CoA} + 7 	ext{CoA-SH} + 7 	ext{FAD} + 7 	ext{NAD}^+ + 7 	ext{H}_2	ext{O} ightarrow 8 	ext{acetyl-CoA} + 7 	ext{FADH}_2 + 7 	ext{NADH} + 7 	ext{H}^+$$

Question 4

Which enzyme is responsible for converting cis double bonds to trans double bonds during the β-oxidation of unsaturated fatty acids?

Accepted Answer

Enoyl-CoA isomerase

Question 5

What is the primary function of bile salts in the digestion of dietary fats?

Accepted Answer

They emulsify fats, increasing the surface area for pancreatic lipase action.

Question 6

Which lipoprotein is primarily responsible for transporting dietary TAGs from the intestine to peripheral tissues?

Accepted Answer

Chylomicron

Question 7

A deficiency in methylmalonyl-CoA mutase leads to the accumulation of which metabolite, resulting in severe acidosis and nervous system damage?

Accepted Answer

Methylmalonic acid

Question 8

During fasting, which process is responsible for the production of ketone bodies in the liver?

Accepted Answer

Ketogenesis

Question 9

Which coenzyme is required for the conversion of propionyl-CoA to succinyl-CoA during the metabolism of odd-numbered fatty acids?

Accepted Answer

Deoxyadenosylcobalamin (Vitamin B$$_{12}$$ derivative)

Question 10

Which hormone stimulates the mobilization of stored fat in adipose tissue during stress situations?

Accepted Answer

Epinephrine

Question 11

What is the role of the carnitine acyltransferase system in fatty acid metabolism?

Accepted Answer

It transports long-chain fatty acyl-CoAs into mitochondria for β-oxidation.

Question 12

Which of the following statements about cholesterol metabolism is TRUE?

Accepted Answer

Excess cholesterol is returned to the liver by HDL for excretion via bile.

Question 13

Which plasma lipoprotein class is most dense and primarily involved in reverse cholesterol transport?

Accepted Answer

HDL

Question 14

Which process is directly responsible for the formation of foam cells in atherosclerosis?

Accepted Answer

Oxidation of LDL and uptake by scavenger receptors in phagocytic cells

Question 15

Which equation correctly represents the net reaction for palmitate biosynthesis from acetyl-CoA?

Accepted Answer

$$8 	ext{Acetyl-CoA} + 7 	ext{ATP} + 14 	ext{NADPH} + 7 	ext{H}^+ ightarrow 	ext{palmitate} + 14 	ext{NADP}^+ + 8 	ext{CoA-SH} + 7 	ext{ADP} + 7 	ext{P}_i + 6 	ext{H}_2	ext{O}$$

Question 16

Which enzyme is the key regulatory point in fatty acid biosynthesis and is activated by insulin?

Accepted Answer

Acetyl-CoA carboxylase (ACC)

Question 17

Why are linoleic and linolenic acids considered essential fatty acids in humans?

Accepted Answer

Humans cannot desaturate fatty acids beyond C9-10.

Question 18

Which vitamin is a derivative of cholesterol and acts analogously to a steroid hormone in regulating calcium and phosphorus metabolism?

Accepted Answer

Vitamin D

Question 19

Which of the following is NOT a class of steroid hormone derived from pregnenolone?

Accepted Answer

Catecholamines

Question 20

Which process is stimulated in diabetes due to impaired glucose utilization, leading to ketoacidosis?

Accepted Answer

Ketogenesis

Lipid Metabolism: Utilization and Transport of Fat and Cholesterol

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