Questions of biochemistry
(سوالات بخش انگلیسی بیوشیمی)
Glycolysis & Gluconeogenesis
Under conditions of hypoglycemia, the liver is not utilizing glucose as an energy source due to which of the following?
(A) A low Km for glucokinase
(B) A high Km for glucokinase
(C) An inhibited, phosphorylated PFK-1
(D) An activated, phosphorylated PFK-1
(E) A reduction of glucose transporters in the membrane
After eating a meal containing carbohydrates, the monosaccharides must be absorbed from the intestinal lumen.This transport is dependent on which of the following enzymes?
(A) Na+/H+ antiporter
(B) Glucose-6-phosphate dehydrogenase
(C) Hexokinase
(D) Chloride transporter
(E) Na+, K+ ATPase
Skeletal muscle PFK-2 is not regulated by phosphorylation, but heart muscle PFK-2 is. In the heart, phosphorylation of PFK-2 leads to what effect?
(A) Enhanced production of fructose-2,6-bisphosphate
(B) Reduced production of fructose-2,6-bisphosphate
(C) Degradation of fructose-1,6-bisphosphate
(D) Increased turnover of PFK-2
(E) Increased transcription of PFK-2
The enzyme aldolase catalyzes:
A. formation of fructose-6-phosphate from glucose-6-phosphate
B. oxidation of the aldehyde group of glucose
C. oxidation of the aldehyde group of glyceraldehyde-3-phosphate
D. conversion of glyceraldehyde-3-phosphate to dihydroxyacetone-phosphate
E. formation of dihydroxyacetone phosphate and glyceraldehyde-3-phosphate from fructose-l,6-bisphosphate
What is the NET yield of NADH when glucose 6-phosphate is oxidized by anaerobic glycolysis to yield lactate?
A. 0
B. 1
C. 2
D. 3
E. 4
In glucose 6-phosphate dehydrogenase deficiency, increased red cell lysis is ultimately due to:
A. problems with ATP production in mitochondria
B. a deficiency in ability to carry out glycolysis
C. increased leakage of K ion into the cells
D. an intrinsic deficiency of membrane structure
E. inability of the cell to maintain normal concentrations of NADPH
Biotin is required as a coenzyme in which one of the following reactions?
A. α-ketoglutarate + NAD + + CoA → succinyl CoA + C02 + NADH
B. pyruvate + CO2 + ATP → oxaloacetate + ADP + Pi
C. pyruvate + NAD + + CoA → acetyl CoA + CO2 + NADH
D. 6-phosphogluconate → ribulose-5-phosphate + CO2
E. α-ketoglutarate + C02 + NADH → isocitrate + NAD +
Glyceraldehyde-3-phosphate dehydrogenase produces which one of the following as a product?
A. inosine triphosphate
B. 1,3-bisphosphoglyceric acid
C. cytidine triphosphate
D. phosphoenolpyruvic acid
E. phosphocreatine
The absence of which one of the following reactions is responsible for the inability of man to use fatty acids in the de novo net synthesis of glucose?
A. oxaloacetate → pyruvate
B. oxaloacetate + acetyl CoA → citrate
C. acetyl CoA→ pyruvate
D. pyruvate → phosphoenolpyruvate
E. phosphoenolpyruvate →oxaloacetate
An allosteric inhibitor of phosphofructokinase is:
A. Alpha-ketoglutarate
B. oxaloacetate
C. citrate
D. isocitrate
E. succinate
What is the NET yield of ATP when glucose 1-phosphate is oxidized by anaerobic glycolysis to lactate?
A. 0
B. 1
C. 2
D. 3
E. 4
