The Question is from neet-botany respiration-in-plants , and it was created by the author K SURESH KUMAR

Question

If the inner mitochondrial membrane were to become permeable to protons, what would be the MOST immediate consequence on ATP synthesis?

K SURESH KUMAR · Accepted Answer

## CORE INFORMATION
✓ **Answer**: B
## CONCEPT FRAMEWORK
 **Primary Concept**: Oxidative Phosphorylation and Chemiosmosis
 **Related Topics**: Mitochondrial structure, ATP synthase, proton motive force
 **Prerequisites**: Understanding of cellular respiration, the electron transport chain, and ATP synthesis.
## SOLUTION PATHWAY
**Given Information**:
  The inner mitochondrial membrane becomes permeable to protons.
  The question asks for the MOST immediate consequence on ATP synthesis.
**Method & Steps**:
 1. Understand the role of the proton gradient in ATP synthesis.
  Reasoning: ATP synthesis in the mitochondria relies on chemiosmosis.  Protons ($H^+$) are pumped from the mitochondrial matrix across the inner mitochondrial membrane into the intermembrane space by the electron transport chain (ETC). This creates a proton gradient (a difference in proton concentration and charge) across the membrane, storing potential energy.
  Formula/Rule:  The proton motive force (PMF) is the driving force for ATP synthesis.  It's determined by both the chemical gradient (difference in $H^+$ concentration) and the electrical gradient (difference in charge).
 2. Analyze the effect of membrane permeability to protons.
  Working: If the inner mitochondrial membrane becomes permeable to protons, the protons will flow back into the matrix down their concentration gradient, bypassing ATP synthase. This dissipates the proton gradient, eliminating the PMF.
  Key Point: The flow of protons through ATP synthase is what drives the synthesis of ATP; without the gradient, this process stops.
 3. Determine the immediate consequence on ATP synthesis.
  Result: The immediate consequence is a complete halt in ATP synthesis driven by the electron transport chain.
  Verification:  The dissipation of the proton gradient directly eliminates the driving force for ATP synthase.  Glycolysis produces a small amount of ATP independently of the mitochondria, but this is not the primary source of ATP and does not alter the fact that mitochondrial ATP synthesis stops.
 ## OPTION ANALYSIS
A :x: Increased proton flow would require a maintained gradient, which is lost in this scenario.
B ✓: Correctly identifies the dissipation of the proton gradient as the immediate cause of halting ATP synthesis.
C :x:  While some ATP is produced via substrate-level phosphorylation during glycolysis, the majority of ATP is produced via oxidative phosphorylation in the mitochondria, which is directly affected.
D :x: While glycolysis continues to produce a small amount of ATP, the immediate and primary effect is the cessation of oxidative phosphorylation.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing substrate-level phosphorylation with oxidative phosphorylation: Remember that oxidative phosphorylation is the major ATP production pathway in aerobic respiration, and it depends on the proton gradient.
  2.Ignoring the importance of the proton gradient: The gradient is crucial for ATP synthesis.  Dissipating it directly affects ATP production.
 **Quick Tips**:
  1.Visualize the inner mitochondrial membrane as a dam holding back water (protons).  If the dam breaks (membrane becomes permeable), the water flows out, and the potential energy is lost.
  2.Remember that ATP synthase is a molecular turbine driven by the proton flow.

K SURESH KUMAR · Answer

ATP synthesis would increase due to increased proton flow.

K SURESH KUMAR · Answer

The correct Option is "ATP synthesis would stop because the proton gradient would dissipate."

K SURESH KUMAR · Answer

ATP synthesis would be unaffected as it relies on substrate-level phosphorylation.

K SURESH KUMAR · Answer

ATP synthesis would decrease, but some ATP would still be produced by glycolysis.

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