Medical Quiz

Lipid Metabolism Quiz


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Name the energy source of the brain during starvation.

A. Fat

B. Ketone bodies

C. Protein

D. Lipids


What is the function of micelles in lipid digestion and absorption?

A. To transport fatty acids and monoacylglycerols across the intestinal cell membranes

B. To emulsify triacylglycerol globules

C. To convert triacylglycerols into chylomicrons

D. To hydrolyze ester linkages in triacylglycerols


Which ketone body is produced first in the process of ketogenesis?

A. Acetoacetate

B. β-hydroxybutyrate

C. Acetone

D. Oxaloacetate


What is the fate of fatty acid entering the cells?

A. Fatty acid diffuses into mitochondria for beta-oxidation

B. Fatty acid is converted into fatty acyl CoA (activated form)

C. Fatty acid is bound to albumin in the cytosol

D. None of the above


Which of the following hormone is not used in the hydrolysis of triacylglycerol into the fatty acids in adipose tissues?

A. Epinephrine

B. Norepinephrine

C. Glucagon

D. Insulin


What is the purpose of the shuttle mechanism in fatty acid transport into the mitochondrial matrix?

A. To convert fatty acids into acetyl CoA

B. To convert acyl CoA into acetyl CoA

C. To convert acetyl CoA into acyl CoA

D. To convert acyl CoA into ketone bodies


What is the primary site for ketogenesis?

A. Liver mitochondria

B. Adipose tissue

C. Muscle cells

D. Pancreas


What are ketone bodies usually synthesized from?

A. Acetyl-CoA

B. Pre-B cell

C. Methionine

D. Pyruvate


What is the role of L-carnitine in fatty acid metabolism?

A. Facilitate the transport of fatty acid from the cytosol to mitochondria

B. Serve as a cofactor for enzyme fatty acid synthase

C. Activator of acetyl CoA carboxylase

D. None of the above


How many ATP molecules are produced from the oxidation of stearic acid, an 18-carbon fatty acid?

A. 120 ATP

B. 122 ATP

C. 124 ATP

D. 126 ATP


Acetyl-CoA are the precursors/ used for these Except

A. Ketogenesis

B. Fatty acid degradation

C. Fatty Acid Synthesis

D. Kreb Cycle


Which of the following is the rate-limiting step of fatty acid oxidation and is also inhibited by malonyl CoA?

A. Thiokinase

B. Carnitine Palmitoyl transferase I

C. Acyl CoA Dehydrogenase

D. Thiolase


Which of the following is NOT a ketone body?

A. Acetoacetate

B. β-hydroxybutyrate

C. Acetone

D. Glycerol


What is lipolysis?

A. Hydrolysis of triacylglycerol

B. Formation of lipids

C. Breakdown of ketone bodies

D. Formation of ketone bodies


Which of the following is not a positive regulator of acetyl CoA carboxylase?

A. Excess calories

B. Insulin

C. Citrate

D. Long-chain fatty acid


What is the main function of adipose tissue?

A. Storage location for energy

B. Insulation

C. Protection against physical shock

D. All of the above


What is the primary site for ketogenesis?

A. Liver mitochondria

B. Adipose tissue

C. Muscle cells

D. Pancreas


What is the purpose of the shuttle mechanism in fatty acid transport into the mitochondrial matrix?

A. To convert fatty acids into acetyl CoA

B. To convert acyl CoA into acetyl CoA

C. To convert acetyl CoA into acyl CoA

D. To convert acyl CoA into ketone bodies


What is the major enzyme involved in the hydrolysis of triacylglycerols in the small intestine?

A. Gastric lipase

B. Pancreatic lipases

C. Hormone-sensitive lipase

D. Lipoprotein lipase


The acetyl CoA is produced in the mitochondria and must be transported into the cytosol for the synthesis of fatty acids. Which of the following is true regarding the transport of Acetyl CoA?

A. Acetyl CoA is diffused from the mitochondrial membrane

B. Acetyl CoA is transported by its specific transporter protein

C. Acetyl CoA is converted into pyruvate, enters into the cytosol and acetyl CoA is regenerated

D. Acetyl CoA is converted into citrate, enters into the cytosol and acetyl CoA is regenerated.


Approximately how many molecules of ATP can be produced from the oxidation of a 20 carbon fatty acid, including those produced in the Krebs cycle?

A. 107

B. 100

C. 129

D. 136


What is the basic order of events in the digestion and mobilization of dietary fats?

A. Degradation by lipases→ emulsified by bile→ incorporation into chylomicrons→ absorption and conversion into triacylglycerols

B. Degradation by lipases→ absorption and conversion into triacylglycerols→incorporation into chylomicrons→ emulsified by bile

C. Emulsified by bile→ degradation by lipases→ absorption and conversion into triacylglycerols→ incorporation into chylomicrons

D. Emulsified by bile→ incorporation into chylomicrons→ absorption and conversion into triacylglycerols→ degradation by lipases


Identify the correct sequential enzymatic step for fatty acid synthesis:

A. Delta-2-enoyl CoA Dehydrate, Acyl CoA Dehydrogenase, Hydroxy acyl dehydrogenase, Thiolase

B. Hydroxy acyl dehydrogenase, Acyl CoA Dehydrogenase, Delta-2-enoyl CoA Dehydrate, Thiolase

C. Thiolase, Acyl CoA Dehydrogenase, Delta-2-enoyl CoA Dehydrate, Hydroxy acyl dehydrogenase

D. Acyl CoA Dehydrogenase, delta-2-enoyl CoA Dehydrate, Hydroxy acyl dehydrogenase, Thiolase


What is the source of NADPH required for fatty acid synthesis?

A. Pentose phosphate pathway

B. Malic enzyme

C. Both

D. None


What enzyme moves carnitine back to the cytoplasm?

A. Ligase

B. Isomerase

C. Translocase

D. Oxidoreductase




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