respiration

• respiration is the release of chemical energy stored in glucose through a series of enzyme controlled reactions
• The energy released when glucose is broken down is used to generate (make) ATP
• what is ATP used for

  • muscle cell contraction
  • cell division
  • protein synthesis 
  • active transport
  • transmission of electrical impulses along a neuron
• stage one of respiration takes place in the cytoplasm, takes place with or without oxygen
• what happens in stage one of respiration ?

  Glucose is broken down to two molecules of pyruvate
• stage one

  glucose is broken down into 2 molecules of pyruvate and 2 molecules of ATP
• stage 2 (aerobic respiration) takes place in the mitochondria, this stage requires oxygen
• stage one produces 2 molecules of ATP
• aerobic respiration produces lots of ATP
• what happens in stage 2 (aerobic respiration)?

  pyruvate is broken down into carbon dioxide and water, and produces lots of ATP
• aerobic respiration word equation

  glucose + oxygen -> carbon dioxide + water + lots of ATP
• fermentation takes place in the cytoplasm and takes place when there is no oxygen available
• fermentation in animal cells

  glucose in broken down into 2 molecules of pyruvate and 2 ATP

  the pyruvate is then converted into lactate

  if oxygen later becomes available the lactate can be converted back into pyruvate
• fermentation in plant and yeast cells 


  glucose is broken down into 2 pyruvate and 2 ATP

  the pyruvate is then converted into carbon dioxide and ethanol (alcohol)

  this process is irreversible
• fermentation in plant and yeast cells word equation

  glucose -> ethanol + carbon dioxide + 2 ATP
• fermentation in animal cells word equation

  glucose -> lactate + 2ATP