Respiration

• Makes pyruvate from glucose by splitting one molecule of glucose (6C) into two molecules of pyruvate (3C).
• This occurs in the cytoplasm and is the first stage of aerobic and anaerobic

1) Phosphorylation

• Glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP
• This creates two molecules of TP and 2 molecules of ADP

2) Oxidation

• Triose phosphate is oxidised (-H) to form 2 molecules of pyruvate
• NAD collects the hydrogen ions, forming 2 reduced NAD
• 4 ATP are produced but 2 were used so there is a net gain of 2

• Converts pyruvate to acetyl coenzyme A
• pyruvate is decarboxylated which produces CO2
• NAD is reduced as it collects the hydrogen from pryruvate, changing pyruvate into acetate
• The acetate then combines with COA to form acetyl COA
• This reaction occurs twice for every glucose molecule

• Produces reduced coenzymes and ATP
• Involves a series of oxidation reactions in the matrix of the mitochondria
• The reaction occurs twice per glucose molecule, once per each pyruvate from the link reaction
• Acetyl COA combines with oxaloacetate to form citrate and the COA molecule goes back to the link reaction to be recycled
• The 6C citrate is decarboxylated to a 5C molecule
• Dehydrogenation also occurs to form reduced NAD from NAD
• The 5C molecule is then converted into a 4C molecule
• Decarboxylation and dehydrogenation occur producing 2 reduced NAD and 1 reduced FAD
• ATP is produced by the direct transfer of a phosphate group from an intermediate compound to ADP (called substrate-level phosphorelation)
• The citrate has been converted to oxaloacetate

Products:

• 1 COA, oxaloacetate, 2 CO2, 1 ATP, 3 reduced NAD, 1 reduced FAD

• Energy carried by electrons from reduced coenzymes is used to make ATP
• There are two processes; Electron transport chain and chemiosmosis
• Hydrogen atoms are released from reduced(r) NAD and rFAD and H splits into protons and electrons
• The electons move along the ETC, losing energy at each carrier
• This energy is used by carriers to pump protons from the matrix to the intermembrane space
• The concentration of protons is now higher in the intermembrane than in the matrix, forming an electrochemical gradient
• Protons move down the electrochemical gradient, back into the mitochondrial matrix via ATP synthase
• This drives the synthesis of ATP from ADP and Pi, this is chemiosmosis
• In the matrix at the end of the transport chain the protons electrons and oxygen combine to form water
• Oxygen is the final electron acceptor

• Only glycolysis occurs
• Pyruvate is coverted into ethanol or lactate during fermentation
• The production of lactate or ethanol regenerates NAD
• This means that glycolysis can continue without oxygen
• Small amounts of ATP will be produced to allow some biological processes to continue