Concept explainers
Interpretation:
The reactions involving glutamate dehydrogenase and glutamine synthetase that produce glutamine from ammonia and
Concept introduction:
Glutamate dehydrogenase is an enzyme present in the mitochondria, which utilizes
In the next step, the formed Schiff base is protonated via hydride transfer from NADPH to form glutamate. Glutamine synthetase enzyme is involved in the
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Biochemistry
- REFLECT AND APPLY The malate-aspartate shuttle yields about 2.5 moles of ATP for each mole of cytosolic NADH. Why does nature use the glycerol-phosphate shuttle, which yields only about 1.5 moles of ATP?arrow_forwardREFLECT AND APPLY The intermediates of glycolysis are phosphorylated, but those of the citric acid cycle are not. Suggest a reason why.arrow_forwardREFLECT AND APPLY Comment on the fact that the reduction of pyruvate to lactate, catalyzed by lactate dehydrogenase, is strongly exergonic (recall this from Chapter 15), even though the standard free-energy change for the half reaction Pyruvate+2H++2eLactate is positive (G=36.2kJmol1=8.8kcalmol1), indicating an endergonic reaction.arrow_forward
- REFLECT AND APPLY Explain how glycogen phosphorylase is controlled allosterically and by covalent modification.arrow_forwardREFLECT AND APPLY In the mitochondrion is a short-chain carnitine acyltransferase that can take acetyl groups from acetyl-CoA and transfer them to carnitine. How might this be related to lipid biosynthesis?arrow_forwardRECALL Outline the steps involved in the production of malonyl-CoA from acetyl-CoA.arrow_forward
- REFLECT AND APPLY Why does the degradation of palmitic acid (see Question 12) to eight molecules of acetyl-CoA require seven, rather than eight, rounds of the -oxidation process?arrow_forwardRECALL Describe the various purposes of the citric acid cycle.arrow_forwardRECALL Describe the role of the F1 portion of ATP synthase in oxidative phosphorylation.arrow_forward
- REFLECT AND APPLY How does the hydrolysis of fructose-1,6-bisphosphate bring about the reversal of one of the physiologically irreversible steps of glycolysis?arrow_forwardRECALL If we describe an enzyme like aspartate transcarbamoylase and say that it exhibits cooperativity, what do we mean?arrow_forwardREFLECT AND APPLY Sulfanilamide and related sulfa drugs were widely used to treat diseases of bacterial origin before penicillin and more advanced drugs were readily available. The inhibitory effect of sulfanilamide on bacterial growth can be reversed by p-aminobenzoate. Suggest a mode of action for sulfanilamide.arrow_forward
- BiochemistryBiochemistryISBN:9781305961135Author:Mary K. Campbell, Shawn O. Farrell, Owen M. McDougalPublisher:Cengage Learning