Question

Under aerobic conditions, when is pyruvate produced and consumed? It is produced in glycolysis and consumed in fermentation.It is produced in electron transport and consumed in glycolysis.It is produced in the citric acid cycle and consumed in electron transport.It is produced in glycolysis and consumed in the citric acid cycle.It is produced in the citric acid cycle and consumed in fermentation.2. What stage of aerobic respiration produces the most ATP? Krebs cyclecitric acid cycleglycolysiselectron transportfermentation

Answer 1

1. The correct answer is: It is produced in glycolysis and consumed in the citric acid cycle

Pyruvate is a molecule that connects metabolic processes of cellular respiration: glycolysis and Krebs (citric acid) cycle. Glycolysis is a process that occurs in the cytosol of the cell and in which several of enzymes catalyze the breakdown of glucose molecules. At the end of glycolysis, products are two pyruvate molecules and released energy (ATP).

After this step, in the matrix of mitochondria oxidation of pyruvate occurs. During this reaction, pyruvate is converted into a three-carbon molecule—acetyl CoA. Acetyl then acts as fuel for the citric acid cycle.

2. The correct answer is: electron transport chain

The amount of ATP produced per glucose is:

Glycolysis: 2 ATP

A process in which glucose is converted into two molecules of pyruvate, ATP is made, NAD+ is converted into NADH.

Krebs Cycle (citric acid cycle): 2 ATP

The acetyl CoA (made from pyruvate) goes through a cycle of reactions. ATP, NADH, FADH2 and CO2 is released.

Electron Transport Chain (oxidative phosphorylation): 28 ATP

Electrons from NADH and FADH2 move down the electron transport chain, protons are pumped out of the matrix, forming a gradient. Gradient of proton is used for the ATP synthesis.

Fermentation: 2 ATP

Breaking down carbohydrates (usually glucose) in the absence of oxygen.