Question

A)

Acetyl coA is made from pyruvate in the [ Select ]   ["mitochondrial matrix", "cytoplasm", "", ""]   by   [ Select ] ["pyruvate dehydrogenase", "succinate dehydrogenase"]         complex. In this process, the acetyl group is moved between enzymes within the complex by the [ Select ] ["lipoamide", "TPP"] . The [ Select ] ["dihydrolipoyl transacetylase", "pyruvate dehydrogenase component"] is the enzyme in which acetyl coA is actually formed. The [ Select ]  ["FADH2", "lipoamide"] in the dihydrolipoyl dehydrogenase donates two electrons to NADH, which then goes on to the electron transport chain.

B)

In the citric acid cycle, [ Select ] ["acetyl coA", "pyruvate"] joins with [ Select ] ["oxaloacetate", "glucose"] to make citrate. Citrate possesses [ Select ] ["six", "three"]         carbons. During the cycle, [ Select ] ["two", "three"] carbons are lost as CO₂. The importance of the cycle is not to generate ATP, but to generate [ Select ] ["reduced electron carriers", "oxidized electron carriers"] , which then go on to the electron transport chain.

Answer 1

Ans: a) Acetyl coA is made from pyruvate in the mitochondrial matrix and pyruvate itself produced from glucose molecule in cytoplasm through a process called glycolysis. This conversion is catalyzed by an enzyme called pyruvate dehydrogenase which basically catalyzes the removal of CO₂ molecule from pyruvate. Pyruvate dehydrogenase present as a component of pyruvate dehydrogenase complex which contains Dihydroxylipoyltransacetylase and dihydrolipoyldehydrogenase apart from pyruvte dehydrogenase, the reaction proceed as decarboxylation of pyruvate followed by transfer of acetyl group to lipolic acid followed by formation of acetyl coA and lipolic acid is reoxidized. The acetyl group is moved between enzymes within the complex by TPP which acts as a coenzyme for this complex. The dihydrolipoyl transacetylase is the enzyme in which acetyl coA is actually formed. The lipoamide in the dihydrolipoyl dehydrogenase donates two electrons that pass first to FAD and then to NAD⁺, so ultimately FADH₂ donates electron to NAD⁺.

b) In citric acid cycle, acetyl coA joins with oxaloacetate to make citrate. Citrate possesses six carbons. During the cycle two carbons are lost as CO₂. The importance o the cycle is to generate reduced electron carries which are NADH and FADH₂, which then go on to the electron transport chain.