Part A activation of pyruvate carboxylase by acetyl-CoA activation of pyruvate c
ID: 221441 • Letter: P
Question
Part A
activation of pyruvate carboxylase by acetyl-CoA
activation of pyruvate carboxylase by acetyl-CoA
Part B
activation of pyruvate dehydrogenase kinase by NADH
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Part C
inhibition of isocitrate dehydrogenase by NADH
inhibition of isocitrate dehydrogenase by { m NADH}
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Part D
activation of isocitrate dehydrogenase by ADP
activation of isocitrate dehydrogenase by { m ADP}
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Part E
inhibition of ? -ketoglutarate dehydrogenase by succinyl-CoA
inhibition of lpha-ketoglutarate dehydrogenase by succinyl-CoA
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Part F
activation of pyruvate dehydrogenase phosphatase by Ca2+
activation of pyruvate dehydrogenase phosphatase by { m Ca^{2+}}
This is a signal that part of available pyruvate can be metabolized into oxaloacetate, when the energy charge is low and production of additional ATP through the citric acid cycle is required. This is a signal that pyruvate can be oxidized in the citric acid cycle instead of shunted into gluconeogenesis. In addition, it is a signal of activation carbohydrate metabolism. This is a signal that pyruvate can be oxidized in the citric acid cycle as well as can be shunted into gluconeogenesis. In addition, it is a signal of activation fat metabolism. This is a signal that pyruvate can be shunted into gluconeogenesis instead of being oxidized in the citric acid cycle. In addition, it is a signal of unbalanced fat and carbohydrate metabolism.Part B
activation of pyruvate dehydrogenase kinase by NADH
activation of pyruvate dehydrogenase kinase by { m NADH}SubmitHintsMy AnswersGive UpReview Part
Part C
inhibition of isocitrate dehydrogenase by NADH
inhibition of isocitrate dehydrogenase by { m NADH}
This tends to activate pyruvate dehydrogenase when level of NADH is sufficient for ATP production via the respiratory chain and, hence, to make pyruvate unavailable for other purposes. This tends to activate pyruvate dehydrogenase when level of NADH is sufficient for ATP production via the cytric acid cycle and, hence, to increase the oxidation of the lipids and carbonhydrates. This tends to inactivate pyruvate dehydrogenase and to activate pyruvate carboxylase and to increase the oxaloacetate production and, hence, to activate gluconeogenesis. This tends to inactivate pyruvate dehydrogenase when level of NADH is sufficient for ATP production via the respiratory chain and, hence, to make pyruvate available for other purposes.SubmitHintsMy AnswersGive UpReview Part
Part D
activation of isocitrate dehydrogenase by ADP
activation of isocitrate dehydrogenase by { m ADP}
This is a signal to reduce flux through the citric acid cycle when metabolism of acetyl-CoA through glyoxylate pathway is more preferred. This is a signal to reduce flux through the citric acid cycle when additional amount of acetyl-CoA is needed for lipid biosynthesis. This is a signal to increase flux through the citric acid cycle when metabolism of acetyl-CoA through glyoxylate pathway is less preferred. This is a signal to reduce flux through the citric acid cycle when levels of reduced electron carriers are adequate for energy generation.SubmitHintsMy AnswersGive UpReview Part
Part E
inhibition of ? -ketoglutarate dehydrogenase by succinyl-CoA
inhibition of lpha-ketoglutarate dehydrogenase by succinyl-CoA
The accumulation of ADP provides a signal to activate the isocitrate dehydrogenase and thereby increase lpha-ketoglutarate level in organism preventing ATP consumption in the process of glutamine desamination. When the energy charge is high, the accumulation of ADP provides a signal to activate the citric acid cycle and thereby increase the succinate production for electron transport chain. When the energy charge is low, the accumulation of ADP provides a signal to activate the citric acid cycle and thereby increase the oxidation of nutrients for ATP production. When the energy charge is high, the accumulation of ADP provides a signal to activate the citric acid cycle and thereby increase the oxidation of nutrients for proteins production.SubmitHintsMy AnswersGive UpReview Part
Part F
activation of pyruvate dehydrogenase phosphatase by Ca2+
activation of pyruvate dehydrogenase phosphatase by { m Ca^{2+}}
This serves as a general indicator that when an energy-rich substrate (succinyl-CoA) is abundant, flux through the citric acid cycle can be reduced. This serves as a signal that there is insufficient amount of NAD+ , FAD , flux through the electron transport should be increased. This allows to increase ? -ketoglutarate accumulation and thereby to increase the rate of amino acids transamination. This allows to turn back reversible stages of the citric acid cycle, to produce additional pyruvate which can be used in gluconeogenesis at high glucose level in the blood. Ca2+ interacts with active sites of four proteins which participate in contraction of vertebrate muscle, which places a huge demand on ATP production. Ca2+ is a critical signaling molecule for contraction in vertebrate muscle, which places a huge demand on ATP production. Ca2+ activates PDH through interaction with an active site of enzyme, when huge amount of ATP molecules is needed for protein synthesis activation. Ca2+ mediates stimulation of PDH activity during muscle contraction, which can produce a huge amound of ATP molecules.Explanation / Answer
Answer
Part A
Pyruvate carboxylase plays an important role in gluconeogenesis. In this process, the pyruvate is converted to pyruvate carboxylase to oxaloacetate, the oxaloacetate is then decarboxylated and phosphorylated to produce phoshoenol pyruvate (PEP) is involved in the synthesis of from pyruvate. Pyruvate carboxylase also acts as a crossroad between lipid and carbohydrate metabolism. Therefore, the correct answer is option (d).
Part B
Pyruvate dehydrogenase kinase (PDK) is activated by ATP, NADH, and acetyl CoA. PDK inactivates pyruvate dehydrogenase by phosphorylating it using ATP. When there are ample amount of fuel is available in the form of acetyl CoA and fatty acids, the activity of pyruvate dehydrogenase is turned off.
Therefore, the correct answer is option (d).
Part C
Isocitrate dehydrogenase is stimulated by ADP and inhibited by NADH. Isocitrate is converted to alpha-ketoglutarate which is an irreversible step and this reaction is initiated by the availability of substrate such as isocitrate, Mg2+, NAD+, or NADP+. If these substrates are depleted or unavailable the reaction will not precede and the reaction can be inhibited by the removal of NADH and also inhibited by ATP feedback from the citric acid cycle. Since, this is a feedback inhibition and citric acid cycle is used to produce ATP, an abundant amount of product will shut down the cycle.
Therefore, the correct answer is option (d).
Part D
ADP is a cofactor that indicates the energy depletion for isocitrate dehydrogenase. The ADP enhances the eznyme’s affinity for the substrate. When isocitrate dehydrogenase is dephosphorylated, it leads to the activation of enzyme which then enters the citric acid cycle and produce ATP.
Therefore, the correct answer is option (c).
Part E
Alpha ketoglutarate dehydrogenase is inhibited by succinyl CoA and NADH. Three reactions of TCA cycle utilize NAD+ as cofactor, the ratio of NAD+/NADH shows a major effect on the flux of carbon through the TCA cycle. Product inhibition also regulates The TCA flux. One example is inhibition of alpha ketoglutarate by succinyl CoA and NADH.
Therefore, the correct answer is option (a).
Part F
The pyruvate dehydrogenase phosphatase is activated by Ca2+ and Mg2+. When there is an increase in Ca2+ levels, the Ca2+ binds to troponin resulting n conformational changes which move tropomyosin and exposing the binding sites and allowing the crossbridges formation which will result in muscle contraction. If there is decrease in Ca2+ levels, the crossbridges cycle will stop.
Therefore, the correct answer is option (b).