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Aerobic Respiration Article

Updated on August 19, 2016

In this article I would like to share the little information I know about Aerobic respiration, please be patient with me I don't know much but this is what I know...

In most organisms energy is released by a process called aerobic respiration, which is dependent on a continuous supply of oxygen from the surroundings.

The site of aerobic respiration

Aerobic respiration is a continuous process but is divided for convenience into three phases. The first phase occurs in the cytoplasm of the cell whilst the remaining two phases occur in the mitochondrion. The number of mitochondris present in any living cell is an indication of the amount of energy required by that cell. Not all of the energy obtained from the breakdown of glucose is used to form ATP. A large amount of energy is lost as heat.

The mitochondrion is well adapted for cellular respiration since the :

  • Outer membrane is smooth thus allowing for easy movement of the mitochondrion through the cytoplasm.
  • Outer membrane is permeable to oxygenand pyruvic acid that is required for the last two phases of cellular respiration.
  • Inner membrane is highly folded to form cristae that increase the surface area for attachment of enzymes.
  • Lumen/matrix of the mitochondrion contains DNA ans ribosomes for the manufacture of enzymes that are required for the cellular respiration.

Aerobic respiration takes place when molecular oxygen is present. The three phases of aerobic respiration are :

  • Glycolysis
  • Kreb's Cycle
  • Oxidative Phosphorylation


  • Glycolysis in the cytoplasmic matrix (cytosol) i.e. outside the mitochondria.
  • It involes the phosphorylation (i.e. addition of energy from ATP) of energy rich compounds such as a 6-carbon glucose molecyule.
  • The activated glucose molecule is broken down step-wise to form two 3-carbon molecules of pyruvic acid.
  • Energized hydrogen atoms and energy are released in the process.
  • The energy is used to form ATP.
  • Each step in the process is catalysed by a highly specific enzyme.

Kreb's Cycle

  • Kreb's Cycle occurs only if oxygen is present.
  • The pyruvic acid pruduced during glycolysis enters the mitochondrion where it is used in a cyclic series of reactions.
  • Energised hydrogen atoms and CO2 are released durind these reactions.
  • Co-enzymes transfer the hydrogen atoms.

Oxidative Phosphorylation

  • This phase of cellular respiration occurs in the mitochondrin.
  • The energized hydrogen atoms (from Glycolysis and Kreb's Cycle) are transferred from one co-enzyme carrier to the next.
  • At each transfer, a little energy from the energized hydrogen is given off.
  • Gradually all the energy is drained off from the hydrogen atoms.
  • This energy is used to combine ADP + P to form ATP.
  • Finally the hydrogen combines with oxygen to form water.

That's all you should know about Aerobic Respiration, now let's learn about Anaerobic on the next post. :)


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