2.2 - cellular respiration

• define cellular respiration?

  a catabolic pathway which provides ATP for other anabolic reactions
• cellular respiration is a series of enzyme controlled reaction
• structure of adenosine triphosphate (ATP)?

  one adenosine molecule and three inorganic phosphate groups (Pi)
• what are the three stages of cellular respiration?

  1. glycolysis
  2. citric acid cycle
  3. electron transport chain
• glycolysis takes place in the cytoplasm
• citric acid cycle takes place in the matrix of mitochondria
• the electron transport chain takes place in the cristae of the mitochondria
• define glycolysis?

  the breakdown of glucose to pyruvate in the cytoplasm
• Pyruvate is converted to acetyl coenzyme A with the loss of carbon dioxide
• the acetyl from acetyl CoA combines with oxaloacetate to form citrate
• dehydrogenases remove hydrogen ions and electrons
• NAD forms NADH
• citrate is converted back into oxaloacetate, resulting in the generation of ATP and the release of carbon dioxide
• the citric acid cycle can only occur in the presence of oxygen (aerobic conditions)
• during glycolysis, there is a net gain of 2ATP
• the energy investment stage is when glucose is converted into intermediates, requiring 2ATP
• the energy pay off stage is where intermediates are converted into pyruvate, releasing 4ATP
• NAD transports hydrogen ions and electrons to electron transport chain
• What molecule produces ATP from ADP + Pi in the electron transport chain?

  ATP synthase
• during the electron transport chain, hydrogen ions combine with electrons and oxygen to form water
• describe the movement of ATP synthase in the electron transport chain?

  rotates
• where does fermentation occur within the cell?

  cytoplasm
• lactate can be converted back into pyruvate if oxygen becomes present
• in animal cells during fermentation, pyruvate is converted to lactate in a reversible reaction
• in plants and yeast during fermentation, pyruvate is converted to ethanol and carbon dioxide
• less ATP are produced during fermentation than in aerobic respiration