Lipid Metabolism

Topics in this chapter

• Fatty Acid Synthesis Regulation
• Beta-Oxidation and Fatty Acid Breakdown
• Ketogenesis and Ketone Metabolism
• Triglyceride Metabolism and Pancreatitis
• Lipoprotein Metabolism and Apolipoproteins
• Cholesterol Synthesis and Pharmacology
• HDL and Reverse Cholesterol Transport
• LDL Receptor and Lipid Disorders

Practice questions

1. Question 1Q-344DAA

   A 32-year-old chronic alcoholic presents with severe abdominal pain and vomiting after a heavy fat-rich meal. Serum amylase and lipase are significantly elevated, and his blood plasma appears milky (turbid). Which of the following lipoprotein complexes is most likely elevated and responsible for the milky appearance of the plasma?

   1. A.Chylomicrons
   2. B.VLDL
   3. C.LDL
   4. D.HDL
   See the answer and solution
2. Question 2Q-2E49E5

   A researcher is studying fatty acid oxidation in isolated rat liver mitochondria. She adds palmitoyl-CoA to the preparation but notes that no beta-oxidation occurs unless she also adds carnitine. Which of the following enzymes is directly responsible for transferring the acyl group from CoA to carnitine?

   1. A.Carnitine palmitoyltransferase I (CPT-I)
   2. B.Carnitine acylcarnitine translocase
   3. C.Carnitine palmitoyltransferase II (CPT-II)
   4. D.Acyl-CoA synthetase
   See the answer and solution
3. Question 3Q-5CB8E7

   A 45-year-old man with a family history of premature coronary artery disease is found to have significantly elevated serum LDL cholesterol levels. Genetic testing reveals a mutation in the ligand-binding domain of the LDL receptor. Which apolipoprotein on the surface of LDL is normally recognized by this receptor?

   1. A.Apo A-I
   2. B.Apo B-48
   3. C.Apo B-100
   4. D.Apo C-II
   See the answer and solution
4. Question 4Q-5DEDA0

   During fasting, the liver produces ketone bodies (acetoacetate, beta-hydroxybutyrate, and acetone) to supply energy to extrahepatic tissues like the brain and skeletal muscle. Which of the following is the rate-limiting enzyme in hepatic ketogenesis?

   1. A.HMG-CoA reductase
   2. B.HMG-CoA synthase (mitochondrial)
   3. C.Thiolase
   4. D.HMG-CoA lyase
   See the answer and solution
5. Question 5Q-B8F24A

   A newborn infant displays failure to thrive, severe hypoglycemia, and hepatomegaly. Biochemical investigations reveal a deficiency in cytosolic carnitine acylcarnitine translocase. This enzyme is crucial for which of the following processes?

   1. A.Transport of acylcarnitine across the inner mitochondrial membrane
   2. B.Synthesis of malonyl-CoA in the cytoplasm
   3. C.Activation of free fatty acids in the cytosol
   4. D.Reduction of double bonds during unsaturated fatty acid oxidation
   See the answer and solution