AP BIOLOGY

Detailed explanation-1: -When NAD+ is converted to NADH, it gains two things: First, a charged hydrogen molecule (H+) and next, two electrons. As electrons are negatively charged, the combination of the positively charged NAD+ and H+, coupled with two electrons, effectively cancel each other out and neutralize the resulting NADH molecule.

Detailed explanation-2: -Due to its chemical structure, each molecule of NAD+ can accept two electrons. This gain of electrons is called reduction, with the electrons coming in the form of a hydrogen atom. In a redox reaction, the hydrogen atom contains two electrons which it shares with the NAD+ molecule.

Detailed explanation-3: -NADH carries the electrons gained from the breakdown of glucose and donates them to the chain of enzymes in mitochondria that are involved in producing ATP (electron transport chain).

Detailed explanation-4: -In the process of fermentation the NADH + H+ from glycolysis will be recycled back to NAD+ so that glycolysis can continue. In the process of glycolysis, NAD+ is reduced to form NADH + H+. If NAD+ is not present, glycolysis will not be able to continue.

Detailed explanation-5: -Thus, the malate–aspartate shuttle is reversible and requires multiple enzymes. In this shuttle, NADH is oxidized to NAD+ in the cytosol and NAD+ is reduced to NADH in mitochondria.