Question

Be able to draw the evolutionary original function of each of the four components of aerobic respiration. Glycolysis, Krebs cycle, electron transport chain, proton pump. As usual, each original appearance should be shown with all inputs (where from) and outputs (where to), and which output was most important. Also, briefly describe what event led to that component's appearance, and how it led to it.

Answer 1

Cellular respiration occurs in 4 phases, i.e., glycolysis, pyruvate processing, citric acid cycle and electron transport chai.

During glyoclysis, glucose is converted into 2 molecules of pyruvate in addition 2 NADH & 2ATP are produced.

The 2 pyruvate molecules undergo oxidative decarboxylation during pyruvate processing and produces 2 molecules of acetylCoA, 2CO2 and 2 NADH.

The 2 AcetylCoA molecules enter in citric acid cycle and completely oxidized to 4 CO2, 6NADH, 2FADH2 & 2ATP.

During electron transport chain, NADH & FADH2 donate electrons and protons. While electrons are transferred from one carrier to other, protons are transferred from mitochnria matrix to intermembrane space. It develops proton concentration gradient. To balance the proton concentration, protons are transprorted from intermembrane space to matrix through ATP synthase. The movement of protons (H+) through ATP synthease enzyme derives energy, which is used to produce ATP from ADP. Thus NADH & FADH2 produce ATP. The protons & electrons are taken accepted by O2 and becomes H2O.