Question

Which of the following reactions are associated with respiration Select one: a. Oxidative phosphorylation b. Glycolysis c. all of the choices d. TCA cycle

Answer 1

Ans (c) : All of the choices

* Glycolysis : In glycolysis, glucose (a six-carbon sugar) undergoes a series of enzyme catalyzed reactions & gets converted into two molecules of pyruvate (three-carbon organic molecule) .Each pyruvate from glycolysis goes into the mitochondrial matrix & gets converted into acetyl CoA.

* Citric acid cycle / TCA cycle : The acetyl CoA made in the last step combines with a four-carbon molecule and goes through a cycle of reactions, ultimately regenerating the four-carbon starting molecule. The net result of citric acid cycle is that for each acetyl group entering the cycle as acetyl-CoA , two molecules of CO₂ are produced.

Acetyl-CoA + 3NAD⁺ + FAD + GDP/ADP +3H₂O -->

2CO₂ + 3NADH + FADH₂ + GTP/ATP + H₂O

* Oxidative phosphorylation : Most of the free energy released during the oxidation of glucose to CO₂ is retained in reduced coenzymes NADH & FADH₂ , generated during glycolysis & TCA cycle. Electrons are released from NADH & FADH₂ & eventually transferred to O₂ , forming H₂O, through electron transport chain.

As electrons move down the chain, energy is released and used to pump protons out of the matrix, forming a gradient. Protons flow back into the matrix through an enzyme called ATP synthase, making ATP.

Hope this will help you?