The different ways in which organisms use ATP
Mitocondria are the sites of certain sites of respiration, in particular the Krebs cycle & the oxidative phosphorylation pathway. They are therefore responsible for the production of the carrier-energy molecule, ATP, from carbohydrates. Because of this, the number, amount of cristae and size of the mitochondria all increase in cells that have a high level of metabolic activity, therefore needing a plentiful supply of ATP.
ATP (adenosine triphosphate), is a nucleotide that consists of 3 components; a 5-carbon sugar (ribose) , an organic base (adenine) and 3 phosphate groups.
One of the stages in respiration is the Krebs cycle which produces reduced co-enzymes and ATP. This cycle involves a series of oxidative-reduction reactions which take place in the matrix of the mitochondria. The cycle happens once for every pyruvate molecule, so therefore goes round twice for every glucose molecule. ATP is produced by the direct transfer of a phosphate group from an intermediate compound to ADP. When a phosphate group is directly transferred from one molecule to another it is called substrate-level phosphorylation. Some products of the Krebs cycle are used in oxidative-phosphorylation which produces lots of ATP. Oxidative-phosphorylation is the process where the energy carried by electrons from reduced co-enzymes ( reduced NAD and reduced FAD ) are used to make ATP. Oxidative phosphorylation involves 2 processes – the elctron transport chain and chemiosmosis. When protons are pumped across the mitochondrial matrix into the intermembrane space an electrochemical gradient is formed. Protons then move down this gradient back into the mitochondrial matrix via ATP-synthase. This movement drives the reaction between adenosine di-phosphate (ADP) and an inorganic phosphate (Pi) molecule. The movement of H+ ions across a membrane, which generates ATP, is called chemiosmosis.
In anaerobic respiration when there is no...