ATP TUTORIAL
THE CELL’S ENERGY CYCLE
ATP GENERATION VS ATP CONSUMPTION
- Aerobic respiration - Chemical work
- Anaerobic respiration - Transport work
- Fermentation - Mechanical work
- Chemolithotrophy
- Phototrophy
- Transport work
ATP ENERGY RICH COMPOUND
- ATP as E currency
- High phosphoryl transfer potential: tendency of an organic molecule to transfer a P group to
an acceptor molecule
- Thermodynamically unfavourable reaction can be converted into a favourable reaction by
coupling it to hydrolysis of the sufficient number of ATPs
- Anhydride bonds act like a coil
- Storage of E
- The bond itself is not special, breakage releases E bc of the chemical/structural properties of
the bond
- ADP is more stable than ATP
Other energy rich compounds: PEP, 1,3-bisphosphate, acetyl-P, acetyl-CoA
, WAYS OF ATP GENERATION
- Substrate level phosphorylation
- Oxidative phosphorylation
- Photophosphorylation
SUBSTARTE LEVEL PHOSPHORYLATION
DEFINITION: SYNTHESIS OF ATP FROM ADP BY PHOSPHORYLATION COUPLED WITH THE EXERGONIC
BREAKDOWN OF A HIGH ENERGY ORGANIC MOLECULE WITH A HIGHER PHOSPHORYL TRANSFER
TENDENCY THAN ATP
1. E from the oxidation of GAP with NAD+ as electron acceptor is used to add a P group to GAP
2. Generation of the E rich compound with a higher P transfer potential tendency, 1,3-
bisphosphoglycerate
3. Redox reaction is coupled to E incorporation, free E is trapped in E rich molecule
4. Substrate level phosphorylation: 1,3-bisphosphoglycerate has a higher P transfer potential tendency
than ATP, the P group is transferred onto ADP to form ATP (reversible reaction)
OXIDATIVE PHOSPHORYLATION
DEFINITION: ELECTRON TRANSPORT INITATED BY THE OXIDATION OF CHEMICAL COMPOUND
- Charge separation leads to the built-up of the membrane potential (pmf)
- Proton motive force is used for ATP synthesis by ATP-synthase
PHOTOPHOSPHORYLATION
DEFINITION: THE SYNTHESIS OF ATP FROM ADP USING E MADE AVAILABLE DURING ELECTRON
TRANSPORT INITIATED BY THE ABSORPTION OF LIGHT E
AUTOTROPHIC PHOTOPHOSPHORYLATION
- The energy for ATP production comes from the light
- Carbon source is CO2
- Two types:
o Oxygenic (donor water to generate NADP for CO2 fixation)
o Anoxygenic (donor something else than water, no O2 production)
THE CELL’S ENERGY CYCLE
ATP GENERATION VS ATP CONSUMPTION
- Aerobic respiration - Chemical work
- Anaerobic respiration - Transport work
- Fermentation - Mechanical work
- Chemolithotrophy
- Phototrophy
- Transport work
ATP ENERGY RICH COMPOUND
- ATP as E currency
- High phosphoryl transfer potential: tendency of an organic molecule to transfer a P group to
an acceptor molecule
- Thermodynamically unfavourable reaction can be converted into a favourable reaction by
coupling it to hydrolysis of the sufficient number of ATPs
- Anhydride bonds act like a coil
- Storage of E
- The bond itself is not special, breakage releases E bc of the chemical/structural properties of
the bond
- ADP is more stable than ATP
Other energy rich compounds: PEP, 1,3-bisphosphate, acetyl-P, acetyl-CoA
, WAYS OF ATP GENERATION
- Substrate level phosphorylation
- Oxidative phosphorylation
- Photophosphorylation
SUBSTARTE LEVEL PHOSPHORYLATION
DEFINITION: SYNTHESIS OF ATP FROM ADP BY PHOSPHORYLATION COUPLED WITH THE EXERGONIC
BREAKDOWN OF A HIGH ENERGY ORGANIC MOLECULE WITH A HIGHER PHOSPHORYL TRANSFER
TENDENCY THAN ATP
1. E from the oxidation of GAP with NAD+ as electron acceptor is used to add a P group to GAP
2. Generation of the E rich compound with a higher P transfer potential tendency, 1,3-
bisphosphoglycerate
3. Redox reaction is coupled to E incorporation, free E is trapped in E rich molecule
4. Substrate level phosphorylation: 1,3-bisphosphoglycerate has a higher P transfer potential tendency
than ATP, the P group is transferred onto ADP to form ATP (reversible reaction)
OXIDATIVE PHOSPHORYLATION
DEFINITION: ELECTRON TRANSPORT INITATED BY THE OXIDATION OF CHEMICAL COMPOUND
- Charge separation leads to the built-up of the membrane potential (pmf)
- Proton motive force is used for ATP synthesis by ATP-synthase
PHOTOPHOSPHORYLATION
DEFINITION: THE SYNTHESIS OF ATP FROM ADP USING E MADE AVAILABLE DURING ELECTRON
TRANSPORT INITIATED BY THE ABSORPTION OF LIGHT E
AUTOTROPHIC PHOTOPHOSPHORYLATION
- The energy for ATP production comes from the light
- Carbon source is CO2
- Two types:
o Oxygenic (donor water to generate NADP for CO2 fixation)
o Anoxygenic (donor something else than water, no O2 production)
