Question

Substrate-level phosphorylation to yield ATP occurs during which stage(s) of aerobic respiration?

	A.	glycolysis
	B.	pyruvate conversion to acetyl-CoA
	C.	tricarboxylic acid cycle (Krebs cycle)
	D.	fermentation
	E.	A and B only
	F.	A and C only
	G.	B and C only
	H.	A, B, C, and D

Answer 1

ANSWER :-

The correct answer is option F ( A and C only) .

Substrate level phosphorylation to yield ATP occurs during glycolysis and TCA cycle.

CELLULAR RESPIRATION -

• A catabolic exergonic oxygen requiring process that use energy extracted from macromolecules like glucose and produce energy (ATP) and water.
• In cellular respiration ATP production takes place through a process called phosphorylation.
• There are two ways of phosphorylation - substrate level phosphorylation and oxidative phosphorylation.

PHOSPHORYLATION -

• The addition of a phosphate to molecule.
• Enzyme used in this process is Kinase.

SUBSTRATE LEVEL PHOSPHORYLATION -

• The synthesis of ATP by the direct transfer of phosphate group from substrate (high energy intermediate ) to a molecule of ADP.
• Reaction is catalyzed by Kinase.
• Instead of phosphate coming from ATP, the phosphate is coming from a molecule and given it to ADP to for ATP.
• This process occurs in glycolysis and TCA cycle or kreb's cycle.

OXIDATIVE PHOSPHORYLATION -

• The use of oxygen (O2) to oxidise electron carriers NADH in order to generate ATP.
• ATP is made through a chemical reaction.
• This process involve Electron transport Chain.
• In compare of substrate level phosphorylation ,oxidatioative phosphorylation produce more ATP.

Other option -

Option A - not valid because substrate level phosphorylation occurs in both glycolysis and TCA cycle.

Option B - not valid ,because there is no production of ATP during process converson of pyurvate to acetyl co-A.

Option C - not valid , because substrate level phosphorylation occurs in both glycolysis and TCA cycle.

Option D - not valid

Option E - not valid

Option F - it is correct.

Option G - not valid

Option H- not valid.

Concept map for understand the process of substrate level phosphorylation and oxidative phosphorylation -