3.5.2 Respiration
4 stages of aerobic respiration:
• Glycolysis (cytoplasm)
• Link reaction (mitochondrial matrix)
• Krebs cycle (mitochondrial matrix)
• Oxidative phosphorylation (cristae)
Glycolysis:
• Respiration produces ATP
• Glycolysis is the first stage of anaerobic and aerobic respiration.
• It occurs in the cytoplasm and is an anaerobic process.
• It involves three steps: Phosphorylating glucose to glucose phosphate
using ATP, the production of triose phosphate and oxidation of triose
phosphate to produce pyruvate with a net gain of ATP and reduced NAD.
Process of glycolysis:
• Glucose is phosphorylated using ATP to produce glucose phosphate.
• Glucose phosphate is split into two molecules of triose phosphate.
• Triose phosphate is then oxidised to produce pyruvate as hydrogen is
removed and is transferred to NAD in which reduced NAD is formed.
• 4 molecules of ATP are produced (2 per triose phosphate) so there is a
net gain of ATP.
The link reaction:
• Pyruvate and reduced NAD (NADH) are actively transported from the
cytoplasm into the mitochondrial matrix.
Process:
• Pyruvate is decarboxylated (1 carbon removed in the form of CO2).
• Pyruvate is oxidised to form acetate (2 carbon molecule). NAD picks up
the hydrogen and becomes reduced NAD.
• Acetate combines with coenzyme A to produce acetylcoenzyme A (2
carbon molecule).
• (No ATP produced in this reaction)
• The link reaction occurs twice for every glucose molecule so:
2x Acetyl CoA
2x CO2 released
2x reduced NAD
Krebs cycle:
4 stages of aerobic respiration:
• Glycolysis (cytoplasm)
• Link reaction (mitochondrial matrix)
• Krebs cycle (mitochondrial matrix)
• Oxidative phosphorylation (cristae)
Glycolysis:
• Respiration produces ATP
• Glycolysis is the first stage of anaerobic and aerobic respiration.
• It occurs in the cytoplasm and is an anaerobic process.
• It involves three steps: Phosphorylating glucose to glucose phosphate
using ATP, the production of triose phosphate and oxidation of triose
phosphate to produce pyruvate with a net gain of ATP and reduced NAD.
Process of glycolysis:
• Glucose is phosphorylated using ATP to produce glucose phosphate.
• Glucose phosphate is split into two molecules of triose phosphate.
• Triose phosphate is then oxidised to produce pyruvate as hydrogen is
removed and is transferred to NAD in which reduced NAD is formed.
• 4 molecules of ATP are produced (2 per triose phosphate) so there is a
net gain of ATP.
The link reaction:
• Pyruvate and reduced NAD (NADH) are actively transported from the
cytoplasm into the mitochondrial matrix.
Process:
• Pyruvate is decarboxylated (1 carbon removed in the form of CO2).
• Pyruvate is oxidised to form acetate (2 carbon molecule). NAD picks up
the hydrogen and becomes reduced NAD.
• Acetate combines with coenzyme A to produce acetylcoenzyme A (2
carbon molecule).
• (No ATP produced in this reaction)
• The link reaction occurs twice for every glucose molecule so:
2x Acetyl CoA
2x CO2 released
2x reduced NAD
Krebs cycle:
