Question

What is NADH? What does it do and how and where is it formed?

Answer 1

Hint: The process of cellular reaction requires several types of molecules which are used in various ways such as in the production of energy and water. The cellular reactions depend upon a number of different enzymes, coenzymes or cofactors.

Complete answer:
NAD or Nicotinamide adenine dinucleotide is an important cofactor and it is an electron acceptor. It is found in all living cells and it exists in two forms NAD and NADH. NADH is the reduced form of the NAD molecule.

NADH is also known as nicotinamide adenine dinucleotide. It is an important pyridine nucleotide found in the body. It mainly functions as an oxidative cofactor in eukaryotic cells. It plays a key role in the production of energy through redox reactions. NADH is necessary for cellular development and energy production in the biological cells. It functions as the principal carrier of electrons in the energy-producing process in the cells. When NAD is converted to NADH, it gains two things which are a charged hydrogen molecule and two electrons. The negatively charged electrons and the combination of the positively charged NAD and H molecule, effectively cancel each other. This neutralizes the reaction and results in the formation of NADH molecules.

The conversion of NAD to NADH, are essential reactions which are important in creating ATP during cellular respiration. Thus, NADH is produced during cellular respiration. In the process of glycolysis and Krebs cycle, NADH molecules are formed from NAD.

While in the electron transport chain, all of the NADH molecules are subsequently split into NAD. The $H^+$ produced are then used to power a sort-of "pump". It takes place on the inner membrane of the mitochondria and a large number of energy molecules or ATP molecules are formed. It further donates electrons to the ETC in the mitochondria. Once the $H^+$ have moved through the cycle, they subsequently merge with the electrons and a molecule of oxygen produces water. All of the three phases of respiration generate ATP; however, the greatest yield of ATP is during the electron transport chain.

Note: The reduced form of NAD is known as NADH. It is generated from glycolysis and other metabolic pathways in the body. NADH is used to make the ATP via electron transport chain (ETC) and oxidative phosphorylation. The conversion of NAD to NADH is very important in the process of formation of ATP during the cellular respiration. It is also used in other important enzymatic reactions of the body.