Question

During cellular respiration, what happens to the 6 carbons in glucose?

a-		All 6 carbons are reduced to CO2.
b-		All 6 carbons are used in the synthesis of ATP.
c-		3 carbons are oxidized to CO2 and 3 carbons are reduced to CO2.
d-		All 6 carbons are completely oxidized to CO2.

Answer 1

Option D

The first step is glycolysis which occurs in the cytoplasm. It is The breakdown of one molecule of glucose into two molecules of pyruvic acid with generation of ATP and NADH.

The second step is decarboxylation of pyruvic acid to form acetyl coenzyme a. It also generates NADH. It occurs in mitochondria. It is known as oxidative decarboxylation or linking reaction or Gateway reaction.

The third step is tricarboxylic acid cycle which is also known as citric acid cycle or kreb cycle. It occurs in mitochondria. It starts with the entry of acetyl coenzyme A. It generates high energy electron carriers, NADH and FADH2. It also generates GTP and various fatty acid intermediates.

The fourth step is electron transport chain which takes place in inner mitochondrial membrane in eukaryotes and in plasma membrane in prokaryotes. It is the passage of electrons from one electron carrier to another. It leads to generation of proton gradient across the mitochondrial membrane which is responsible for spinning of ATP synthase.

The last step is synthesis of ATP which occurs by the spinning of enzyme ATP synthase. This is known as chemiosmosis.

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