Biochemistry Practice Questions XIII with Answers

 

21. When NADH produced in cytoplasm is used for respiration through the malate-asparate shuttle, how many protons will be pumped to the intermembrane space?

 

22. A consequence of the malate-asparate shuttle is that mitochondrial glutamate is indirectly moved to cytoplasm. Thus, this process cannot be sustained unless glutamate is provided to mitochondria. What is the name of the metabolic process providing glutamate to mitochondria?

 

23. In F1 F0 ATP synthase, how many molecules of ATP will be synthesized when the γ subunit rotates 360°?

 

24. When there are 12 c subunits in an F1 F0 ATP synthase complex, how many H+ molecules need to translocalize to produce 1 molecule of ATP?

 

25. When there are 9 c subunits in an F1 F0 ATP synthase complex, how many H+ molecules need to translocalizae to produce 1 molecule of ATP?

 

26. Considering that typical F1 F0 ATP synthase complex has 12 c subunits, and considering that 1 H+ is needed to transport ADP from cytoplasm to mitochondria, how many ATP will be produced by the oxidation of one NADH?

 

27. Considering that typical F1 F0 ATP synthase complex has 12 c subunits, and considering that 1 H+ is needed to transport ADP from cytoplasm to mitochondria, how many ATP will be produced by the oxidation of one FADH2?

 

28. Considering that typical F1 F0 ATP synthase complex has 12 c subunits, and considering that 1 H+ is needed to transport ADP from cytoplasm to mitochondria, how many ATP will be produced by the oxidation of one acetyl CoA?

 

29. Considering that typical F1 F0 ATP synthase complex has 12 c subunits, and considering that 1 H+ is needed to transport ADP from cytoplasm to mitochondria, how many ATP will be produced by the oxidation of one pyruvate?

 

30. Considering that typical F1 F0 ATP synthase complex has 12 c subunits, and considering that 1 H+ is needed to transport ADP from cytoplasm to mitochondria, how many ATP will be produced by the oxidation of one glucose (assuming that cytosolic NADH is consumed through glycerol-3-phosphate shuttle)?

 

31. Let’s imagine that there is a drug that binds to the NADH-Q oxidoreductase and prevents it pumping H+ to intermembrane space (other functions are assumed as not altered). How many molecules of ATP can be produced when one molecule of NADH is consumed through ETC in this situation?

 

The above curve is showing the effect of adding ADP to mitochondria on the consumption of oxygen. Uncoupling protein 1 (UCP1) is a protein that can move H+ from intermembrane space to mitochondrial matrix. What will happen to the graph if UCP1 is overexpressed? Draw expected results.

32. The above curve is showing the effect of adding ADP to mitochondria on the consumption of oxygen. Uncoupling protein 1 (UCP1) is a protein that can move H+ from intermembrane space to mitochondrial matrix. What will happen to the graph if UCP1 is overexpressed? Draw expected results.

33. Acetyl coenzyme A produced from mitochondria should be converted to __c_____ to be transported out of mitochondria.

34. ATP citrate lyase plays an important role of producing cytoplasmic acetyl CoA in human. However, yeast cells do not have ATP citrate lyase. How would yeast cells produce cytoplasmic acetyl coenzyme A?

35. Acetyl CoA Carboxylase (ACC) is an enzyme converting acetyl coenzyme A to malonyl CoA. ACC is phosphorylated by AMPK. Malonyl-CoA is used as an inhibitor of fatty acid oxidation. What will happen to fatty acid oxidation when cells are treated with metformin?

36. When cells are treated with statin, what will happen to cellular biosynthesis of ubiquinone?

 

37. HMG-CoA reductase is an enzyme phosphorylated by AMPK. What will happen to cholesterol biosynthesis if cells are treated with metformin?

 

38. What is the name of protein that senses cholesterol level in cells?
A. Insig
B. SCAP
C. SREBP
D. LDH receptor
E. S1 protease

39. Cyclic AMP phosphodiesterase (cAMP PDE) is an enzyme that converts cyclic AMP to AMP. If cAMP PDE is overexpressed in liver, then ____________________. Select all correct statements.
A. glucagon will not bind to its receptor
B. G protein will not be activated by glucagon-binding to the receptor
C. Adenylyl cyclase will not be stimulated by glucagon-binding to the receptor
D. PKA will not be activated by glucagon-binding to the receptor
E. Glycogen phosphorylase will not be phosphorylated upon glucagon-binding to the receptor

40. When glucose transporter in pancreatic β cells are replaced with one with a higher Km for glucose, ___________________________. Select all correct statements.
A. there will not be any effect on insulin secretion.
B. pancreatic β cells will secret insulin constitutively.
C. pancreatic β cells will secret insulin at higher blood glucose concentration.
D. There will be more glycogen accumulating in liver
E. There will be less glycogen accumulation in liver

41. IRS-1 is a substrate for protein kinase C (PKC) which inhibits insulin signaling. When PKC is constitutively activated, __________________. Select all correct statements.
A. Insulin will not bind to the insulin receptor
B. Insulin receptor will not be phosphorylated
C. IRS-1 will be not be phosphorylated by the insulin receptor.
D. PI3K will not be activated
E. PIP2 will not be phosphorylated to PIP3

42. Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme producing NADPH. This is believed to be a major source of cytoplasmic NADPH. When G6PD is completely inhibited,____________.
A. cholesterol biosynthesis will be activated.
B. fatty acid biosynthesis will be activated
C. nucleotide biosynthesis will be activated.
D. Reduced glutathione will be accumulated.
E. More glucose will be used for glycolysis.

43. When 3 molecules of glucose-6-phosphate are converted to 2 molecules of fructose-5-phosphate and one molecule of glyceraldehyde-3-phosphate by pentose phosphate pathway, how much energy production is lost?
A. 0 ATP
B. 1 ATP
C. 2 ATP
D. 3 ATP
E. 4 ATP