Substrate-level phosphorylations play critical roles in generating energy (ATP)

Question

Substrate-level phosphorylations play critical roles in generating energy (ATP) especially during anaerobic respiration. Choose the set of enzymes that catalyse substrate-level phosphorylation reactions (a)Pyruvate kinase, Creatine phosphokinase, ATP synthase, Succinyl CoA (b) Succinyl CoA synthetase, Pyruvate kinase, Creatine phosphokinase, (c) Pyruvate kinase, Phosphoinositide 3-kinase, Acetyl CoA synthetase, (d) Phosphoglycerate kinase, Pyruvate kinase, Succinyl CoA synthetase, ATP (e)Creatine phosphokinase, Acetyl CoA synthetase, Phosphoglycerate kinase synthetase. Phosphoglycerate kinase. Phosphoglycerate kinase. synthase Pyruvate kinase Although the pyruvate dehydrogenase complex is subject to allosteric control, especially inhibition by reaction products, the main regulatory process controlling the enzymes activity in eukaryotes is (a)high energy charge switches the pyruvate dehydrogenase complex on. (b) phosphorylation by ATP that turns on the complex and dephosphorylation that turns it off phosphorylation by ATP that turns off the complex and dephosphorylation that turns it on. (c) (d)exchange of ADP and ATP on the pyruvate dehydrogenase complex. (e) reversibility of the formation of acetyl CoA from pyruvate. ATP is the fuel and energy currency of living cells. ATP synthase operates like a molecular turbine, rotating within a membrane to turn ADP and inorganic phosphate (Pi) to ATP. In 1997 the Nobel Prize in Chemistry was awarded to which of the following scientists for "elucidation of the enzymatic mechanism underlying the synthesis of adenosine triphosphate (ATP)"? (a) Paul D. Boyer (b) John W. Cornforth (c) Peter D. Mitchell (d)Jens C. Skou (e)John E. Walker

Explanation / Answer

1) Substrate-level phosphorylation play critical roles in generating energy (ATP) especially during anaerobic respiration, Choose the set of enzymes that catalyse substrate level phosphorylation reaction

ANSWER IS: B. Succinyl CoA synthetase, pyruvate kinase, phosphoglycerate kinase, creatine phosphokinase.

EXPLANATION:

Let's begin with concepts...

Substrate level phosphorylation defined as direct addition of a phosphate group to an ADP molecule that generates ATP. It is phosphorylation of ADP to ATP without mitochondrial electron transport chain and ATP synthase.

Oxidative phosphorylation generate ATP through a trans-membrane protein called ATP synthase.

So in options where ATP synthase are used are not correct.

Examples...

A) Glycolysis

In glycolysis, substrate level phosphorylation reactions catalyzed by phosphoglycerate kinase and pyruvate kinase that produces ATP.

B) citric acid cycle

Succinyl CoA synthetase is enzyme in the citric acid cycle that catalyzes formation of ATP by substrate-level phosphorylation.

C) one more example of Substrate level phosphorylation is seen in the phosphocreatine pathway and the enzyme for this pathway is creatine phosphokinase.

2) Although the pyruvate dehydrogenase complex is subject to allosteric control, especially
inhibition by reaction products, the main regulatory process controlling the enzymes' activity in eukaryotes is

ANSWER IS: Phosphorylation by ATP that turns the complex off and dephosphorylation that turns it on.

High levels of ATP means situation where no further ATP is needed and therefore, the enzyme is turned off by phosphorylation.

3) ANSWER IS : Paul D. Boyer

EXPLANATION:

Paul D. Boyer, a molecular biologist who was awarded in the 1997 with Nobel Prize in Chemistry.

Dr. Boyer discovered mechanism for ATP formation by ATP synthase. He said it's function related with turbine.

Turbine run in reverse by electrically driven water pump. This is analogous to what the ATP synthase, where it uses the energy of ATP hydrolysis.

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.