Final answer:
The reduced form of nicotinamide adenine dinucleotide (NAD+) is NADH, achieved by adding two electrons and a proton to NAD+. This form is crucial in energy transfer within cells during metabolic reactions.
Step-by-step explanation:
Reduced Form of Nicotinamide Adenine Dinucleotide (NAD+)
The coenzyme nicotinamide adenine dinucleotide, commonly known as NAD+, plays a critical role in the redox reactions within cells. It exists in two forms: an oxidized form (NAD+) and a reduced form (NADH). The reduced form of NAD+ is known as NADH, which results from the acceptance of two electrons and one proton (a hydrogen atom) by NAD+. This process typically occurs during metabolic reactions where NAD+ accepts electrons from organic molecules, thus acting as an electron carrier within the cell.
In the terms of molecular changes, NAD+ has a nicotinamide ring that can accept a hydrogen ion (proton) and two electrons, resulting in the formation of NADH. The conversion involves the addition of two H+ ions and two electrons (2H+ + 2 e¯) to the NAD+ molecule. NADH can then carry these electrons to other molecules in the cell, thus enabling the transfer of energy and serving as an important part of cellular respiration.
Nicotinic acid, also known as niacin, is converted to nicotinamide before it combines with a ribose phosphate to form NAD+. Additionally, NAD+ can be phosphorylated to create nicotinamide adenine dinucleotide phosphate (NADP+), which also acts as a coenzyme in various cellular reactions.