Topic 7: Run for your Life
Respiration
Aerobic Respiration
Aerobic respiration is made of four stages: glycolysis, the link reaction, the Krebs cycle and
oxidative phosphorylation. During aerobic respiration, glucose is effectively burned inside our
bodies (it reacts with oxygen) to produce carbon dioxide, water and lots of energy in the form of ATP.
The overall equation for aerobic respiration is:
Glycolysis
The first stage of aerobic respiration is glycolysis, which takes place in the cytoplasm. Glycolysis
converts glucose, a six-carbon molecule, into two smaller three-carbon molecules called pyruvate.
This stage doesn’t require oxygen so it is an anaerobic process and is involved in both aerobic and
anaerobic respiration pathways.
, Glucose is phosphorylated using the phosphate groups from two molecules of ATP. ATP is
hydrolysed into ADP and inorganic phosphate. This forms a molecule which is unstable and
immediately breaks down into two three-carbon molecules called triose phosphate (TP). Hydrogen is
removed from TP to convert it into pyruvate. The hydrogen is transferred to a coenzyme called NAD
to form reduced NAD (NADH). The removal of hydrogen from TP oxidises it. The reduced NAD is
used in the last stage of aerobic respiration, oxidative phosphorylation, whereas the pyruvate moves
into the mitochondria for the next stage of respiration, the link reaction.
The conversion of triose phosphate to pyruvate produced four molecules of ATP. Since two molecules
were used for the phosphorylation of glucose in the first step, this means there is a net gain of two
ATP molecules in glycolysis.
Respiration
Aerobic Respiration
Aerobic respiration is made of four stages: glycolysis, the link reaction, the Krebs cycle and
oxidative phosphorylation. During aerobic respiration, glucose is effectively burned inside our
bodies (it reacts with oxygen) to produce carbon dioxide, water and lots of energy in the form of ATP.
The overall equation for aerobic respiration is:
Glycolysis
The first stage of aerobic respiration is glycolysis, which takes place in the cytoplasm. Glycolysis
converts glucose, a six-carbon molecule, into two smaller three-carbon molecules called pyruvate.
This stage doesn’t require oxygen so it is an anaerobic process and is involved in both aerobic and
anaerobic respiration pathways.
, Glucose is phosphorylated using the phosphate groups from two molecules of ATP. ATP is
hydrolysed into ADP and inorganic phosphate. This forms a molecule which is unstable and
immediately breaks down into two three-carbon molecules called triose phosphate (TP). Hydrogen is
removed from TP to convert it into pyruvate. The hydrogen is transferred to a coenzyme called NAD
to form reduced NAD (NADH). The removal of hydrogen from TP oxidises it. The reduced NAD is
used in the last stage of aerobic respiration, oxidative phosphorylation, whereas the pyruvate moves
into the mitochondria for the next stage of respiration, the link reaction.
The conversion of triose phosphate to pyruvate produced four molecules of ATP. Since two molecules
were used for the phosphorylation of glucose in the first step, this means there is a net gain of two
ATP molecules in glycolysis.
