Respiration

HideShow resource information

Respiration

The conversion of glucose into ATP takes place during cellular respiration. There are two different forms of cellular respiration:

  • Aerobic respiration - this requires oxygen and produces carbon dioxide, water and ATP.
  • Anaerobic respiration - this takes place in the absence of oxygen and produces lactate in animals or ethanol and carbon dioxide in plants. Only a little ATP is produced.

Aerobic respiration can be divdied into four stages:

  • Glycolysis - the splitting of the 6C glucose molecule into 2x 3C pyruvate molecule.
  • Link reaction - the conversion of the 3C pyruvate molecules into carbon dioxide and 2C acetylecoenzyme A.
  • Krebs cycle - the introduction of acetylcoenzyme A into a cycle of oxidation-reduction reations, that yeild some ATP and large numbers of electrons.
  • Oxidative phosphorylation - the use of electrons produced in the Krebs cycle to synthesise ATP with water produced as a by-product.

Glycolysis

  • Glycolysis is the initial stage of both aerobic and anaerobic respiration.
  • It occurs in the cytoplasm of the cell.
  • It occurs in the following stages:
  • Glucose is phosphorylated by adding 2 phosphate molecule from 2 molecules of ATP
  • This created 2x 3C triose phosphate moleulce and 2 molecules of ADP.
  • The 2x 3C triose phosphat molecules are oxidised by losing hydrogen, forming 2x 3C pyruvate molecules.
  • The two hydrogen molecules are collected by NAD to for 2x reduced NAD molecules.
  • 4 ATP are produced, but 2 were used up to lower the activation energy of glucose, so theres a net gain of 2 ATP molecules.
  • The two molecules of reduced NAD go to the last stage - oxidative phosphorylation.
  • The two pyruvate molecules go into the matrix of the mitochondria for the ling reaction.

Link Reaction

  • This takes place in the matrix of the mitochondria.
  • The pyruvate molcules produced in the cytoplasm during glycolysis are actively transported into the matrix of the mitochondria.
  • It occurs in the following stages:
  • The 3C pyruvate molecules are oxidised, by removing hydrogen and losing a carbon atom in the form of carbon dioxide.
  • NAD collects the hydrogen atom to form reduced NAD and carbon dioxide is released as a waste product.
  • This results in the 3C pyruvate molcules to change into 2C acetate.
  • Acetate is then combined with coenzyme A,

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »