In the conversion of glucose into two molecules of lactate, the NADH generated earlier in the pathway is oxidized to NADT.+Why is it not to the cell's advantage to simply make more NAD so that the regeneration would not be necessary?++NAD synthesis requires ATP, so it is more energetically favorable to use NAD catalytically and couple its recyclingto lactate production.++Catalytic use of NAD would require the synthesis of a new molecule of NAD each time a molecule of pyruvate wasproduced from glucose.++Stoichiometric use of NAD would require the synthesis of a new molecule of NAD for every molecule of pyruvateconverted to lactate.++There is no cellular pathway to synthesize new NAD molecules, so recycling is the only means by which NADlevels are maintained.

NAD is an electron carrier. It carries electrons from substrate oxidation to the ETC to generate a…

Answered: Why is it not to the cell's advantage…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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In the conversion of glucose into two molecules of lactate, the NADH generated earlier in the pathway is oxidized to NAD +. Why is it not to the cell’s advantage to simply make more NAD+ so that the regeneration would not be necessary? After all, the cell would save much energy because it would no longer need to synthesize lactic acid dehydrogenase.
ATP levels are high in the liver, NADPH levels are low, but fat biosynthesis needs to happen. What is the function of the pentose phosphate pathway? Mode 1 - NADPH and ribose 5-phosphate are being generated Mode 2 - ribose 5-phosphate is needed, so only the non-oxidative portion is being used for carbon skeleton rearrangments Mode 3 - NADPH is needed, so oxidative portion is operating to make NADPH and non-oxidative portion is operating to regenerate glucose 6-phosphate Mode 4 - NADPH and ATP are needed, so oxidative portion makes NADPH, non-oxidative portion does carbon skeleton rearrangements to fuel glycolysis and make ATP
Which of the following statements best explains why the activity of ATP-citrate lyase and malic enzyme are often paired together? The use of ATP by ATP-citrate lyase means that NADH needs to be regenerated cytosolically so that more ATP can be generated via shuttle systems and replace the ATP used by ATP-citrate lyase ATP-citrate lyase produces ATP and malic enzyme produces NADPH, both needed in the fatty acid biosynthetic pathway The activity of ATP-citrate lyase and malic enzyme never are correlated, they always function in different realms of metabolism The generation of acetyl CoA is a substrate for fatty acid synthesis in the cytosol and NADPH is generated as the anabolic electron carrier
The image below shows part of a key catabolic pathway. If an individual had a deficiency for the enzyme required at point "X", would they still be able to produce a high rate of ATP during very strenuous exercise? ATP in Glucose Prep. phase Payoff phase ļ - MacRoc Pyruvate →→→ Anaerobic fate of pyruvate ATP out ▬OD OF 1- HP 01 -- Select one: O a. No, because NAD* will not be regenerated by lactate dehydrogenase. The reduction of NAD+ to NADH is a required step during the payoff phase of glycolysis. O b. No, because lactate dehydrogenase is required for the continued recycling of NAD+ to NADH, thus allowing glycolysis to continue. Oc. Yes, because pyruvate dehydrogenase is necessary to produce acetyl-CoA, which under these conditions will feed into the citric acid cycle. Od. Yes, because this enzyme is responsible for the substrate-level phosphorylation necessary to maintain the ATP input for the preparatory phase of glycolysis. DE Report question issue Notes + 14:12 ( CE
C000 C000 NADH NAD -NADH NAD* oco, NAD Oco,- FADH NADH FAD ATP ADP+,P Select the conclusion that would most accurately explain the impact on the Krebs Cycle if glycolysi were to slow down its rate of reaction. ATP production would increase since glycolysis would be using less ATP. The Krebs cycle production of FADH2 would increase. O The Krebs cycle would continue to function at a normal rate. O The Krebs cycle production of NADH would decrease.
When muscles contract, a chain of events result in greater activity by the TCA cycle. All of the following are links in that chain EXCEPT: The ADP concentration increases. Rate of respiration and oxygen consumption increases. The electron transport chain produces more water. The concentration of NADH decreases and the concentration of NAD+ increases. 2) (True or False )______The concentration of oxaloacetate drops and TCA cycle is halted which leads to the synthesis of ketone bodies. 3) NADPH is used for: a) Oxidizing vitamin E b) Oxidizing glutathione c) Reductive biosynthesis of fatty acids d) β-oxidation of fatty acids
Which of the following statements is correct about oxidative pentose phosphate pathway? Group of answer choices It generates NADH It oxidizes NADPH to NADP+ The pathway supplies ribose 5-phosphate and NADPH in the quantities the cell requires Glucose 6-phosphatase catalyzes the rate-limiting reaction of the pathway
A more recent role of E2 within the pyruvate dehydrogenase complex involves localization to the nucleus to act in which of the following? Signal transduction Block electron transport Enhanced levels of ATP biosynthesis Aid in apoptosis Enhanced proton motive force
Consider a mutant hepatocyte cell in which the Q-cycle was not used and teh two electrons from ubiquinone both went sequentially directly to cytochrome c. What would be the total ATP yeild for oxidation of a molecule of glucose this mutant? ATP
Briefly, explain why the transfer of electrons from NADH to the ETC results in the production of more ATP molecules than are produced as a result of the transfer of electrons from FADH2?
Consider the function of the cofactor FAD. Which of the following makes it unique (different) from NAD+? Select all that apply. Operates as part of an enzyme and is not a mobile electron carrier In its fully reduced state, carries 2 electrons Involved in electron transfers as part of pyruvate dehydrogenase complex activity O Facilitates single electron transfers
Fill in the blanks for Succinate Dehydrogenase. 2 succinates to 2 fumarates produce: 1 ⒸFADH₂ So starting with 1 six carbon glucose, up to this point a total of 2 2 CO₂, 2 2 GTP, 2 NADH have been produced. Incorrect answer ATP, ⒸFADH₂ and

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