Question

Define, differentiate, tell the cellular location and give an example of each of the two different types of ways a mammalian cell can generation ATP from ADP and Pi.

Answer 1

Two ways of ATP production are Substrate level phosphorylation and Oxidative phosphorylation.

Substrate level phosphorylation happens in the cytosol mainly during glycolysis. During this process a higher energy compund is converted to a lower energy compund by several enzymes. This released energy is used to create bond between phosphoryl group and ADP to create ATP. Energy is stored in these phosphate bonds.This mode of ATP production is less efficient and don't require an electron donor and the process is very quick.

Oxidative phosphorylation happens in the inner membrane of mitochondria. It is a pathway in which cells uses enzymes to oxidise nutrients there by releasing energy of oxygen which is used to produce ATP. The reducing equivalents that are produced during Glycolysis and krebs cylce like NADH and FADH donates electrons to the ETC. Electrons pass through different complexes in the mitochondrial membrane causing a potential different across the matrix and inner membrane space. This potential difference leads to the flow of H+ ions through ATP synthase to mitochondrial matrix. Flow of electrons cause conformational change in ATP synthase and it uses this mechanical energy to produce ATP from ADP and pi. The electron is finally accepted by oxygen.

Unlike substrate level phosphorylation , this process is slow, and has better efficiency.