What is the importance of NADH and FADH2 in respiration?

NADH and FADH2 are crucial in respiration as they carry high-energy electrons to the electron transport chain.

NADH (Nicotinamide Adenine Dinucleotide) and FADH2 (Flavin Adenine Dinucleotide) are coenzymes that play a vital role in cellular respiration, specifically in the process of oxidative phosphorylation. They act as electron carriers, transporting high-energy electrons and protons to the electron transport chain (ETC) located in the inner mitochondrial membrane.

During the stages of glycolysis and the Krebs cycle, glucose is broken down and energy is released. This energy is used to reduce NAD+ and FAD to NADH and FADH2 respectively. Each NADH molecule is capable of carrying two high-energy electrons along with a proton, while each FADH2 molecule carries two electrons but no protons.

The high-energy electrons carried by NADH and FADH2 are then transferred to the ETC. As these electrons move down the chain, they release energy which is used to pump protons across the mitochondrial membrane, creating a proton gradient. This gradient drives the synthesis of ATP (Adenosine Triphosphate), the main energy currency of the cell, through a process known as chemiosmosis.

In essence, NADH and FADH2 are crucial for the conversion of the energy stored in glucose into a form that can be readily used by the cell. Without these coenzymes, the process of cellular respiration would not be efficient, and the cell would not be able to produce sufficient energy to carry out its functions. Therefore, understanding the role of NADH and FADH2 in respiration is fundamental to understanding how cells generate and utilise energy.