A metabolic pathway that replenishes an intermediate that has been used up is ca
ID: 132133 • Letter: A
Question
A metabolic pathway that replenishes an intermediate that has been used up is called
a) amphibolic.
b) anabolic.
c) anaplerotic.
d) catabolic.
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The molecule that enters the Krebs cycle to regenerate citric acid by reacting with malate is: a) acetyl CoA. b) pyruvate. c) 3-phosphoglycerate. d) glyceraldehyde 3-phosphate.
The final metabolite produced by -oxidation of fatty acids is:
a) acetyl CoA.
b) pyruvate.
c) 3-phosphoglycerate.
d) glyceraldehyde 3-phosphate.
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The bacterium Brucella abortus can utilize the tetrose erythritol as a carbon source. The concentration of erythritol within a B. abortus cell is 10 mM, while the external erythritol concentration is at levels as low as 0.20 mM. What is the energy requirement for the inward transport of erythritol at 37°C under these conditions? Hint: You may use the equation below. Hint: In this case, T = 37 °C = 310 K.
a) DGinward = +2,409.7 cal/mol·°
b) DGinward = –2,409.7 cal/mol·°
c) DGinward= +1,046.5 cal/mol·°
d) DGinward= –1,046.5 cal/mol·°
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Cystic fibrosis is a term that describes a syndrome produced by defective Cl– channels in humans or their lack of intracellular transport from the ER to the plasma membrane. Why would a cystic fibrosis patient have mucus accumulation in the lungs?
a) Mucus biosynthesis enzymes need Cl–.
b) Water molecules that keep the interior of the lungs wet leave cells as solvation spheres for Cl–.
c) Cl– breaks the interactions between mucus and alveolar cells; its absence leads to mucus
accumulation.
d) It is not known.
Explanation / Answer
A metabolic pathway that replenishes an intermediate that has been used up is called c) anaplerotic. Example=> TCA cycle intermediates are used for biosynthesis of various metabolites, so cells need to replenish these intermediates to meet the energy demand. Few anaplerotic reactions are (i) carboxylation of pyruvate to oxaloacetate, (ii) transamination of aspartate to oxaloacetate, (iii) hydration of glutamate to ?-ketoglutarate, (iv) ?-oxidation of fatty acids to succinyl-CoA.
The molecule that enters the Krebs cycle to regenerate citric acid by reacting with malate is: a) acetyl CoA. Pyruvate from glycolysis undergoes oxidative decarboxylation to yield Acetyl CoA which combines with oxaloacetate to for citrate.
The final metabolite produced by -oxidation of fatty acids is: a) acetyl CoA. Acetyl CoA enters TCA cycle to undergo p r odi e ATP via oxidative phosphorylation.