AP BIOLOGY

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CELL RESPIRATION

OXIDATIVE PHOSPHORYLATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Oxidative phosphorylation produces by far the most molecules of ATP per molecule of glucose. In this process electrons flow down an electron transport chain providing energy to pump electrons from the mitochondrial matrix to the intermembrane space, creating a proton gradient. Once enough of a gradient has been formed, the protons flow through an ATP synthase which synthesizes ATP from ADP. Certain chemicals can disrupt this system for the purpose of thermoregulation or other reasons. In the 1930’s a chemical called dinitrophenol (DNP) was used as a dieting aid. The chemical acts as an ionophore, allowing protons to leak across the mitochondrial membrane. Why would poking holes in the mitochondrial membrane interfere with the electron transport chain?
A
It would be harder to establish a H+ gradient to do work.
B
NADH and FADH2 could not be oxidized
C
It would not be able to reduce oxygen
D
It would cause protons to flow from the stroma to the thylakoid membrane
Explanation: 

Detailed explanation-1: -Oxidative phosphorylation produces 24–28 ATP molecules from the Kreb’s cycle from one molecule of glucose converted into pyruvate.

Detailed explanation-2: -ATP generation in oxidative phosphorylation is significantly greater than glycolysis alone, due to the efficiency of energy extraction in the electron transport chain (ETC).

Detailed explanation-3: -During oxidative phosphorylation, electrons derived from NADH and FADH2 combine with O2, and the energy released from these oxidation/ reduction reactions is used to drive the synthesis of ATP from ADP.

Detailed explanation-4: -Oxidative phosphorylation, the process where electron transport from the energy precursors from the citric acid cycle (step 3) leads to the phosphorylation of ADP, producing ATP. This also occurs in the mitochondria.

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