Overview of Cellular Respiration

C6H12O6 + 6O2 → 6CO2 + 6H2O + 36 ATP

Cellular respiration is the process of converting glucose and oxygen to carbon dioxide and water to produce energy. Almost all organisms use glucose as their main energy molecule. Even plants, which are well known to use carbon dioxide and water for life, perform cellular respiration with the glucose they obtain from photosynthesis. All autotrophs (which use light to make glucose) and heterotrophs (which feed on other organisms to get glucose) perform cellular respiration.

Cellular respiration is a catabolic reaction where complex glucose is broken down into simpler molecules of water and carbon dioxide, thus releasing energy which can then be used by the organism for movement or for heat. Each smaller step that makes up cellular respiration needs a small activation energy to occur and releases a small block of energy (this is due to enzymes). This means that it is easier to convert the released energy to ATP and store it for later use.

Big Goals

1

To break the bonds between the carbon atoms in glucose, to make carbon dioxide

2

To move hydrogen atoms from glucose to oxygen to make water


3

To trap any energy made in the process and convert it to ATP


Four Stages

  1. Glycolysis - breaking down glucose into 2 pyruvate chains

  2. Pyruvate Oxidation - converting pyruvate to acetyl-coA in the presence of oxygen

  3. Kreb's Cycle - breaking acetyl-coA apart into carbon dioxide

  4. Electron Transport Chain - converting NADH and FADH produced to ATP

Each of these cycles take place in a different part of the cell according to how they work. Glycolysis happens in the cytoplasm of the cell, right after oxygen has been absorbed through the cell wall. Pyruvate oxidation and Kreb's cycle happen in the mitochondrial matrix, and the ETC takes place in the membrane of the mitochondria. The ETC uses this small space to build up a gradient.