Skills: Cell Respiration (DP IB Biology: HL)

• The stages of respiration can be shown and summarised by different reactions which are shown in diagrams involving chemical molecules
• The diagrams can be used to deduce where oxidation and decarboxylation occur
  • Decarboxylation is the removal of a carbon from a reaction, that releases carbon dioxide
  • Oxidation is either the gain of oxygen, or the loss of electrons or hydrogens

Identifying decarboxylation in aerobic respiration

Identifying oxidation in the electron transport chain

• The structure of a mitochondrion can be investigated by transmission electron microscopy
• Electron micrographs of a mitochondrion may differ in appearance depending on where the cross-section occurs
• The clarity of electron micrographs make it possible to produce a line drawing to show the mitochondrion’s double membrane around the matrix, and the way the inner membrane folds to form cristae
• Typically, mitochondrial drawings should show the following features:
  • Usually sausage-shaped in appearance
  • Inner membrane contains many internal protrusions (cristae)
  • Intermembrane space is very small
  • Ribosomes and mitochondrial DNA are usually not visible at standard resolutions and magnifications

Electron micrograph of a mitochondrion, with an interpretive drawing of the adaptations annotated