CHE 327 Biochemistry

Cholesterol Synthesis

100

Does your body make all the cholesterol it needs? Briefly explain.

Yes, your liver makes all the cholesterol you need.

200

All 27 carbon atoms of cholesterol are derived from:

A. Acetyl CoA

B. Acetoacetyl CoA

C. Propionyl CoA

D. Succinyl CoA

E. Malonyl CoA

A

300

These type of drugs help lower the patient's LDL-C in the blood. What are these drugs called?

Statins

400

Cholesterol is a precursor for the following except:

A. Taurocholate

B. Glycocholate

C. Calcitriol

D. Corticosteroids

E. Calcitonin

E

500

Acetyl CoA serves as the precursor for the synthesis of cholesterol, and the biosynthesis of cholesterol is tightly regulated. Which of the following step is a regulatory step of cholesterol biosynthesis. 

a) Formation 3-hydroxy-3-methylglutaryl COA

b) Formation of Mevalonate 

c) Formation of Isoprenoid Unit

d) Formation of Lanosterol

B

Fatty Acid Synthesis

100

The biosynthesis of triacylglycerols from acetate occurs mainly in: 

A) animals but not in plants.

B) humans after ingestion of excess carbohydrate. 

C) humans with low carbohydrate intake.

B

200

When the liver converts excess glucose into fatty acids, all of the following are true EXCEPT

1. Glucose is converted by glycolysis into pyruvate in the cytosol
2. Acetyl CoA and oxaloacetate form citrate that leaves the mitochondria
3. Pyruvate is converted to acetyl CoA by pyruvate dehydrogenase in the cytosol
4. Citrate lyase converts citrate, CoA and ATP into oxaloacetate, acetyl CoA, ADP and Pi

C

300

In comparing fatty acid biosynthesis with  oxidation of fatty acids, which of the following statements is incorrect?

A) A thioester derivative of crotonic acid (trans-2-butenoic acid) is an intermediate in the synthetic path, but not in the degradative path.

B) Fatty acid degradation is catalyzed by cytosolic enzymes; fatty acid synthesis by mitochondrial enzymes. 

C)Fatty acid biosynthesis uses NADPH exclusively, whereas Beta-oxidation uses NAD+ exclusively.  

 

B

400

When the liver converts excess glucose into fatty acids, all of the following are true EXCEPT

1. The control enzyme is acetyl CoA carboxylase
2. The enzyme is activated by protein phosphatase
3. Protein phosphatase is activated as a result of glucagon binding to liver cells
4. The control enzyme converts ATP, CO2, and acetyl CoA into malonyl CoA, ADP, and Pi
5. The concentrations of glucagon, epinephrine, or AMP are low because high concentrations would inhibit the control enzyme

C

500

During fasting or exercise, fatty acids need to enter the mitochondria. All of the following will increase entry EXCEPT

1. insulin
2. AMP
3. increased active protein kinase A
4. epinephrine
5. glucagon in the liver

A

Critical Thinking

100

Explain briefly why we require fats in our diets.

Dietary fats provide the linoleate and linoleate that we need (for eicosanoid synthesis) but cannot synthesize.

200

**Dr. Google will be needed for this question**

A child is was brought to the hospital with the clinical presentation of mental retardation, blindness, and muscular weakness. The biochemical examination showed the accumulation of GM2 gangliosides in the tissues. What is the possible cause of the disease?

a) Tay Sachs Disease caused by Hexosaminidase A deficiency

b) Fabry Disease caused by Alpha-Galactosidase deficiency

c) Krabbe Disease caused by Beta-Galactosidase deficiency

d) Gaucher Disease caused by Beta-Glucosidase deficiency

A

300

Which of the following glycolytic intermediates serves as the precursor for the backbone for the synthesis of Triglycerides, Phosphatidylcholine, Phosphatidylethanolamine?

a) Glyceraldehyde-3-phosphate

b) Pyruvate

c) 1-3 Bisphosphoglycerate

d) 3-Phosphoglycerate

A

400

Which of the following enzyme is responsible for the conversion of cholesterol to cholesterol ester inside the cells?

a) Lecithin Cholesterol Acyl Transferase

b) Acyl CoA Cholesterol Acyl Transferase

c) Cholesterol Esterase

d) None of the Above

B

500

Hormones such as insulin & glucagon regulate HMG CoA reductase by a phosphorylation and dephosphorylation process. Phosphorylation of HMG CoA reductase results in decreased enzyme activity.  Identify the correct statement from the following

a) Insulin inhibits kinase that phosphorylates HMG CoA reductase

c) Insulin activates kinase that phosphorylates HMG CoA reductase

c) Insulin activates the phosphatase that removes a phosphate group from HMG CoA reductase

d)  Insulin inhibits kinase that phosphorylates HMG CoA reductase

C