Question

Describe the molecular mechanisms of mitochondrial ATP synthesis

biochem

Answer 1

Mitochondria in eukaryotic cells are membrane bound organelles which are esponsible for cellular energy production. mtDNA encodes 13 proteins which are essential for respiratory chain function. It comprises of an inner and outer membrane separating the aqueous regions, the intermembrane space and the matrix. Mitochondria has cellular function includes calcium signalling, cell growth, differentiation, cell cycle control and cell death. It is tightly regulated by processes like fission and fusion, biogenesis and autophagy.

Oxygen is used for mitochondrial respiration which builds a proton gradient on the expanded surface area of the cristae. It is the proton gradient, mainly drives much of mitochondrial physiology causising the synthesis of adenosine triphosphate (ATP). It involves transfer of calcium along with other ion exchangers, and also there is import of proteins. Oxidative phosphorylation is also regulated by cellular calcium signalling, where there is transfer of Ca²⁺ ions into the mitochondrial matrix signals by oxidative phosphorylation by upregulating the rate limiting enzymes of the citric acid cycle. Excessive mitochondrial Ca²⁺ uptake is important in the brain, heart and muscle.

The mitochondria has enzymatic systems which are used for complete oxidation of sugars, fats and proteins.This is used produce usable energy in the form of ATP9. These substrates can be catabolised to acetyl-CoA, which then enters into: the citric acid cycle, which occurs in the mitochondrial matrix.Sugars after undergoing glycolysis in the cytosol enter the mitochondria as pyruvate which is facilitated by acetyl-CoA. Inside the mitochondria, fatty acids are converted to acetyl-CoA by Beta oxidation.