Cell Respiration

Respiration involves oxidative-reduction reactions (redox). An electron moves from one reactant to another. The reactant that loses an electron (and energy) is oxidized; the reactant that gains an electron (and energy) is reduced. In respiration, electrons are taken from the glucose (along with a H proton) and move to an electron carrier such as NAD+. NAD+ is reduced and takes in two electrons and a H proton (H+) to become NADH.

Glycolysis is considered to be substrate level phosphorylation. This means that a substrate donate a phosphate to ADP to make ATP.  The electron transport chain is oxidative phosphorylation which is when electrons give up energy to form ATP.

The electron transport chain consist of 3 transmembrane proteins embedded in the inner membrane. These transmembranes act hydrogen pumps to push H+ from the matrix into intermembrane space. There are also two carrier molecules that work to move electrons between the proteins. Electrons are dropped off from NADH at the first protein and from FADH2 at the first carrier molecule. As the electrons move through the chain they lose energy which is used to pump the hydrogen through the transmembrane proteins (hydrogen pumps). A high concentration of H+ is formed in the intermembrane space; H+ move back to the lower concentration through the ATP synthase which will phosphorylate ADP into ATP. Turing the potential energy from a H+ concentration into usable ATP is called chemiosmosis. 

Glycolysis = 2 ATP, 2 NADH, 2 pyruvate

​Transition step = 2 acteyl CoA, 2 CO2, 2 NADH

Krebs/citric acid cycle = 4 CO2, 6 NADH, 2 FADH2, 2 ATP

Electron transport chain = 26-30 ATP, 6H2O