1.6 - respiration

• what is respiration?

  • respiration is the release of chemical energy stored in glucose through a series of enzyme - controlled reactions
• what is ATP?

  • ATP is a high energy molecule
  • When the end bond in the molecule of ATP is broken energy is released
• what is the role of ATP?

  the energy transferred by ATP can be used for cellular activities such as:

  • muscle cell contraction
  • cell division
  • protein synthesis
  • active transport
  • transmission of electrical impulses along a neuron
• what is the first stage of respiration called?

  • glycolysis (in the cytoplasm)
• explain the first stage of respiration (glycolysis)


  a glucose molecule is broken down by a series of enzyme controlled reactions into two molecules of pyruvate.

  • This process is called glycolysis and does not require oxygen
  • it also releases enough energy to regenerate 2 molecules of ATP
  • Takes place in the cytoplasm
• explain the second stage of respiration (breakdown of pyruvate)

  the next stage of aerobic respiration requires oxygen.

  • it takes placed in the mitochondria
  • each molecule of pyruvate is broken down to carbon dioxide and water
  • this yields (produces) a large number of ATP molecules
• what is the equation for aerobic respiration?

  glucose + oxygen $\rightarrow$ carbon dioxide + water + energy
• what is fermentation?

  • fermentation occurs when there is no oxygen present
  • it involves the partial breakdown of glucose
  • glycolysis occurs as normal, releasing its 2 ATP molecules
  • It takes place in the cytoplasm
• what happens with fermentation in animal cells?

  • glucose is broken down to two molecules of pyruvate
  • this states yields (produces) 2 molecules of ATP
  • As there is no oxygen avaliable, the pyruvate molecules are converted into lactate
  • if oxygen is avaliable, lactate can be converted back into pyruvate
• what happens with fermentation in plant and yeast cells?

  • glucose is broken down to two molecules of pyruvate
  • the stage yields (produces)2 molecules of ATP
  • If there is oxygen present, the pyruvate molecules are converted to carbon dioxide and ethanol (a type of alchol)
  • This is irreversible
• give the word equation for aerobic respiration?

  glucose + oxygen $\rightarrow$ carbon dioxide + water + large number of ATP
• give the word equation for fermentation in animal cells?

  glucose $\rightarrow$ lactate + 2 ATP
• give the word equation for fermentation in plant and yeast cells

  glucose $\rightarrow$ carbon dioxide + ethanol + 2 ATP
• what are mitochondria the site of?

  • aerobic respiration
• explain mitochondria

  mitochondria are the site of aerobic respiration and where most of the ATP is made.

  • if a cell contains many mitochondria, it must require a lot of energy
  • eg. sperm cells to swim to the egg, muscle cells for movement and neurons to transmit electrical impulses
• what factors effect the rates of respiration?

  • type of organism
  • number of organisms present
  • temperature as respiration is controlled by enzymes
• how can you measure the rates of respiration?

  • the rate of respiration can be measured by using a respirometer