Respiration

Contents:

  • Glycolysis
  • Link reaction
  • Krebs cycle
  • Electron transport chain
  • Anaerobic respiration
  • Energy yields from aerobic and anaerobic respiration
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  • Created by: Emilie
  • Created on: 17-06-15 15:17
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Respiration
Glycolysis
Glycolysis is the initial stage of both aerobic and anaerobic respiration. It occurs in the cytoplasm
of all living cells and is the process by which a hexose sugar, usually glucose, is split into two
molecules of the 3-carbon molecule pyruvate .
1. Activation of glucose by phosphorylation. Before it can be split into two, glucose must first be
made more reactive by the addition of two phosphate molecules. These come from the
hydrolysis of ATP to ADP and Pi.
2. Splitting of the phosphorlylated glucose. Each glucose molecule is split into two triose
phosphate molecules.
3. Oxidation of triose phosphate. Hydrogen is removed from each of the two triose phosphate
molecules and transferred to a hydrogen-carrier molecule known as NAD to form reduced
NAD.
4. Production of ATP. Enzyme controlled reactions convert each triose phosphate into pyruvate.
In the process, two molecules of ATP are regenerated from ADP.
Glycolysis has a net yield of 2 ATP and 2 NADH.
Link reaction
The pyruvate produced in glycolysis are actively transported to the matrix of mitochondria. Here it
undergoes a series of reactions during which the following changes take place:
The pyruvate is oxidised by removing hydrogen. This hydrogen is accepted by NAD to form
reduced NAD, which is later used in the electron transport chain to produce ATP.

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The 2C molecule that is thereby formed combines with coenzyme A to produce acetyl CoA.
A carbon dioxide molecule is formed from each pyruvate.
pyruvate + NAD + CoA acetyl CoA + NADH + CO2
Reaction happens twice per molecule of glucose.
Krebs cycle
The Krebs cycle involves a series of redox reactions that take place in the matrix of mitochondria.…read more

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Once pumped across the membrane, the protons cannot pass back through, therefore a high
concentration of H+ is present in the intermembrane space.
The protons therefore diffuse through a carrier protein which contains the enzyme ATP
synthase.
Energy from the diffusing protons also allows ADP to be phosphorylated to form ATP.
Oxygen (inhaled) is the terminal acceptor of the electrons. This then combines with the
protons to form water.…read more

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