Lecture 8 – Cellular Processes, Respiration, Photosynthesis
, • Energy Flow
- Autotroph (plant)
Photosynthesis and Respiration.
- Heterotroph (animal/fungus)
Respiration (not breathing) = oxidation of organic compounds to release
energy (ATP).
- We use energy for active processes. Expend energy in the form of atp in
order to get something done. E.g. making complex molecules from
monomers.
- Energy for movement. E.g. segregation of chromosomes, muscle contraction.
- Active transport uses energy. Moving compounds or ions against their
concentration gradient.
- Energy for production of heat = Body uses the law of thermodynamics.
• Thermodynamics
1st LAW = Energy can neither be created nor destroyed but it can be transferred or
transformed.
2nd LAW = The universe tends to disorder (entropy).
• Gibbs Free Energy
“The energy available to do work.”
Measured as g. Change in free energy = change in heat – temperature in Kelvin x
change in entropy.
Favourable = Spontaneously (not instantaneous). Will go forward without energy
input.
Unfavourable = Not spontaneous. Need energy to go in in order for the reaction to
go forward.
Endergonic Reaction
- Unfavourable – not spontaneous.
- Reaction favours reactants.
, - +ve Delta G
- Delta G > 0
Exergonic Reaction
- Energy is released
- Favourable – Spontaneous (no energy is needed for the reaction to go
forward).
- -ve delta G
- Delta G < 0
• Equilibrium
- Reversible reaction.
- Does not go to completion.
- No net change. No change in amount of products and reactants. Occurring
at the same rate ~ Dynamic equilibrium (forward and backward reaction at
same rate).
• Le Chatelier’s Principle
“ When a system at equilibrium is changed, the system adjusts to absorb that
change.”
• Oxidation and Reduction
Oxidation = Loss.
Reduction = gain.
• Biological Oxidation and
Reduction
Hydride Ions H+.
, • Energy Flow
- Autotroph (plant)
Photosynthesis and Respiration.
- Heterotroph (animal/fungus)
Respiration (not breathing) = oxidation of organic compounds to release
energy (ATP).
- We use energy for active processes. Expend energy in the form of atp in
order to get something done. E.g. making complex molecules from
monomers.
- Energy for movement. E.g. segregation of chromosomes, muscle contraction.
- Active transport uses energy. Moving compounds or ions against their
concentration gradient.
- Energy for production of heat = Body uses the law of thermodynamics.
• Thermodynamics
1st LAW = Energy can neither be created nor destroyed but it can be transferred or
transformed.
2nd LAW = The universe tends to disorder (entropy).
• Gibbs Free Energy
“The energy available to do work.”
Measured as g. Change in free energy = change in heat – temperature in Kelvin x
change in entropy.
Favourable = Spontaneously (not instantaneous). Will go forward without energy
input.
Unfavourable = Not spontaneous. Need energy to go in in order for the reaction to
go forward.
Endergonic Reaction
- Unfavourable – not spontaneous.
- Reaction favours reactants.
, - +ve Delta G
- Delta G > 0
Exergonic Reaction
- Energy is released
- Favourable – Spontaneous (no energy is needed for the reaction to go
forward).
- -ve delta G
- Delta G < 0
• Equilibrium
- Reversible reaction.
- Does not go to completion.
- No net change. No change in amount of products and reactants. Occurring
at the same rate ~ Dynamic equilibrium (forward and backward reaction at
same rate).
• Le Chatelier’s Principle
“ When a system at equilibrium is changed, the system adjusts to absorb that
change.”
• Oxidation and Reduction
Oxidation = Loss.
Reduction = gain.
• Biological Oxidation and
Reduction
Hydride Ions H+.
