AP BIOLOGY

Detailed explanation-1: -Glycolysis depends on a continuous supply NAD+. Without NAD+ the reaction which converts glyceraldehyde-3-phosphate to 1, 3 biphosphoglycerate cannot take place and the process comes to a halt. The need to regenerate NAD+ is why cells undergo fermentation in the absence of oxygen.

Detailed explanation-2: -Nicotinamide adenine dinucleotide (NAD+) is an important molecule in glycolysis. It is a cofactor which regulates metabolism through its electron transport function in the redox reaction in glycolysis and the TCA cycle, In glycolysis, NAD+ reduces forming NADH and H+. If NAD+ is absent, glycolysis cannot continue.

Detailed explanation-3: -If NAD+ is not present, glycolysis will not be able to continue. During aerobic respiration, the NADH formed in glycolysis will be oxidized to reform NAD+ for use in glycolysis again.

Detailed explanation-4: -NAD+ is mostly used in catabolic pathways, such as glycolysis, that break down energy molecules to produce ATP. The ratio of NAD+ to NADH is kept very high in the cell, keeping it readily available to act as an oxidizing agent. NADH is used in the electron transport chain to provide energetic electrons.

Detailed explanation-5: -Energy payoff phase. In a series of steps that produce one NADH and two ATP, a glyceraldehyde-3-phosphate molecule is converted into a pyruvate molecule. This happens twice for each molecule of glucose since glucose is split into two three-carbon molecules, both of which will go through the final steps of the pathway.