RESPIRATION revision notes
AQA specification, A level
Table of contents
• Respiration
• Glycolysis
• Link Reactions
• Krebs cycle
• The ETC chain
• Chemiosmosis
• ATP
• Anaerobic pathways
• Respirometers
By Dr Anusha Ramessur
, Respiration
• Aerobic respiration requires oxygen and produces carbon dioxide, water and much ATP,
complete breakdown, uses variety of substrates.
• Anaerobic respiration: absence of oxygen, produces lactate (in animals) or ethanol and
carbon dioxide (in plants and fungi),and only a little ATP, only glucose as substrate,
incomplete breakdown
Aerobic respiration can be divided into 4 stages:
1. Glycolysis - splitting of 6C glucose molecule into 2 x 3-carbon pyruvate molecules.
2. Link reaction -the 3 C pyruvate molecules enter into a series of reactions leading to the
formation of acetyl-coenzyme A (2C)
3. Krebs cycle -the introduction of acetyl-coenzyme A into a cycle of oxidation-reduction
reactions that yield some ATP and a large quantity of reduced NAD and FAD.
4. Oxidative phosphorylation -the use of the electrons, associated with reduced NAD and
FAD, released from the Krebs cycle to synthesise ATP with water produced as a by-product.
, Respiration
▪Process in which respiratory substrates (e.g glucose, fatty acids, amino acids )are broken
down to release energy used to synthesise ATP.
▪Many cells use only glucose as respiratory substrate. Others can use fatty acids, glycerol
and amino acids.
▪Complete oxidation of glucose in aerobic respiration:
C6H12O6 + 6 O2 6CO2 + 6H2O + 2870 kj
▪ Glucose stable molecule. Cannot be lysed
easily to release energy.
▪How the cell lyses glucose ? By
▪(1) lowering activation energy using enzymes,
▪(2) Raising energy level of glucose through phosphorylation allowing it to split easily.
▪Glucose breakdown in aerobic respiration divided in 4 stages:
▪ (1) Glycolysis
▪ (2) Link reaction
▪ (3) Krebs cycle (mitochondrial matrix)
▪ (4) Oxidative phosphorylation (electron transport in inner membrane of mitochondrion)
AQA specification, A level
Table of contents
• Respiration
• Glycolysis
• Link Reactions
• Krebs cycle
• The ETC chain
• Chemiosmosis
• ATP
• Anaerobic pathways
• Respirometers
By Dr Anusha Ramessur
, Respiration
• Aerobic respiration requires oxygen and produces carbon dioxide, water and much ATP,
complete breakdown, uses variety of substrates.
• Anaerobic respiration: absence of oxygen, produces lactate (in animals) or ethanol and
carbon dioxide (in plants and fungi),and only a little ATP, only glucose as substrate,
incomplete breakdown
Aerobic respiration can be divided into 4 stages:
1. Glycolysis - splitting of 6C glucose molecule into 2 x 3-carbon pyruvate molecules.
2. Link reaction -the 3 C pyruvate molecules enter into a series of reactions leading to the
formation of acetyl-coenzyme A (2C)
3. Krebs cycle -the introduction of acetyl-coenzyme A into a cycle of oxidation-reduction
reactions that yield some ATP and a large quantity of reduced NAD and FAD.
4. Oxidative phosphorylation -the use of the electrons, associated with reduced NAD and
FAD, released from the Krebs cycle to synthesise ATP with water produced as a by-product.
, Respiration
▪Process in which respiratory substrates (e.g glucose, fatty acids, amino acids )are broken
down to release energy used to synthesise ATP.
▪Many cells use only glucose as respiratory substrate. Others can use fatty acids, glycerol
and amino acids.
▪Complete oxidation of glucose in aerobic respiration:
C6H12O6 + 6 O2 6CO2 + 6H2O + 2870 kj
▪ Glucose stable molecule. Cannot be lysed
easily to release energy.
▪How the cell lyses glucose ? By
▪(1) lowering activation energy using enzymes,
▪(2) Raising energy level of glucose through phosphorylation allowing it to split easily.
▪Glucose breakdown in aerobic respiration divided in 4 stages:
▪ (1) Glycolysis
▪ (2) Link reaction
▪ (3) Krebs cycle (mitochondrial matrix)
▪ (4) Oxidative phosphorylation (electron transport in inner membrane of mitochondrion)
