Aerobic Respiration (SQA National 5 Biology): Revision Note

The mitochondria

• Aerobic respiration requires oxygen and takes place in cellular organelles called mitochondria (singular = mitochondrion)

• The structure of the mitochondrion is such that aerobic respiration can occur efficiently to generate ATP

• Each mitochondrion has the following structures:

  • A double membrane

  • A folded inner membrane for a large surface area

    • This is where respirations occur

  • An inner fluid-filled space

    • This contains enzymes essential for respiration

• Many cells that require a large supply of ATP (such as sperm cells, nerve cells and muscle cells) have a large number of mitochondria

The process of aerobic respiration

• Aerobic respiration takes place over several reactions

• Initially, glucose enters a cell and is broken down into two molecules of pyruvate

  • This releases enough energy to make two ATP molecules

  • This stage occurs in the cytoplasm rather than in mitochondria

• If oxygen is present, each pyruvate is broken down (by enzyme-controlled reactions) completely into carbon dioxide (CO₂) and water (H₂O)

  • This process releases lots of energy

  • Enough energy is released to make a large number of ATP molecules

  • These enzyme-controlled reactions take place in the mitochondria

The word equation for aerobic respiration