BIochem - Bioenergetics Flashcards
What kind of reactions are all reaction in the cells which involve the transfer of energy?
Oxidation reduction reactions - ATP -> ADP + P is oxidation
The transfer of energy in the body depends on what?
Movement of electrons
What is the energy currency of the cell?
ATP
How does ATP carry energy ?
3 phosphoryl groups are added to ATP via 1 phosphoester bond and 2 phosphoanhydride bonds
When the bonds are broken energy is released
What is hydrolysis ?
A chemical reaction involving the breaking of a bond using water
Equation for hydrolysis of ATP
ATP + H2O -> ADP + Pi (HPO4 ^ 2-) + ENERGY
All endergonic reactions in a cell require a corresponding exergonic reaction t/f?
True
What is energy coupling?
An energetically favourable reaction with an energetically unfavourable one
What are the laws of thermodynamics?
- Energy can’t be created or destroyed
- In any closed system entropy will either remain constant or increase - the universe always tends towards increasing disorder
What is enthalpy ?
The internal energy in a system
What is entropy ?
The randomness/disorder in a system
What is Gibb’s free energy?
The amount of energy that is capable of doing work during a reaction at a constant temperature and pressure
Equation of Gibb’s free energy
Δ G = Δ H – T Δ S
Explain the equation of GIbb’s free energy
At a constant tempterature The change in free energy is determined by the enthalpy change (reflecting the no. And kinds of covalent bonds broken and formed) and the entropy change (change in systems disorder)
What happens to free energy when ΔH = T ΔS
ΔG = 0 , no change in free energy
What happens when ΔH > T ΔS
Δg is positive, reaction is endergonic
What happens when ΔH < T ΔS
ΔG negative - reaction is exergonic
Is a biochemical reaction has a negative ΔG , will it occur spontaneously ?
Yes
Is a biochemical reaction has a positive ΔG , will it occur spontaneously ?
No. Requires energy
What is free energy ?
The energy cells must use to do things
Why can’t heat be used by cells to carry out reactions?
Cells function at a constant temperature - they are isothermal
What does NADPH stand for
Nicotinamide adenine dinucleotide phosphate
What is ΔH
The change in enthalpy of a system. Refers to the number and type of bonds which are created/destroyed
What is ΔS?
The change in entropy in a system
