AP BIOLOGY

Detailed explanation-1: -The tricarboxylic acid (TCA) cycle, also known as the Krebs or citric acid cycle, is the main source of energy for cells and an important part of aerobic respiration. The cycle harnesses the available chemical energy of acetyl coenzyme A (acetyl CoA) into the reducing power of nicotinamide adenine dinucleotide (NADH).

Detailed explanation-2: -Glycolysis, the first step of cellular respiration, occurs in the cytoplasm of your cells. During this process, a glucose molecule is broken down into two molecules of pyruvate (pyruvic acid).

Detailed explanation-3: -Krebs cycle or TCA cycle takes place in the matrix of mitochondria under aerobic condition. Step 1: The first step is the condensation of acetyl CoA with 4-carbon compound oxaloacetate to form 6C citrate, coenzyme A is released. The reaction is catalysed by citrate synthase.

Detailed explanation-4: -Once pyruvate is converted to acetyl CoA, it enters the Krebs cycle (also known as the citric acid cycle). The Krebs cycle is an eight–step cycle in which acetyl CoA is added to oxaloacetate, which is further broken down producing CO2, reduced coenzymes (NADH + H+ and FADH2), and ATP.

Detailed explanation-5: -First step: Citrate Synthase In the first reaction (see Figure) of the Krebs cycle, acetyl-CoA reacts with oxal acetate. Acetyl-CoA is coupled (yellow background) with the C2 atom of the oxal acetate and the C6 body citryl-CoA is formed. This is a high-energy thioester bound in the enzyme, and it is not released.