Bioenergetics Flashcards
What is metabolism?
A co-ordinated set of chemical reactions catalysed by enzymes
What do energetics dictate?
The rates & equilibrium positions of reactions
What does a closed system eventually reach?
Equilibrium
What does an open system eventually reach?
A steady state
What is the 1st law of thermodynamics?
The law of conservation of energy.
Total amount of energy in a system stays the same but can be found in different forms.
What is enthalpy?
The heat absorbed during a reaction at constant pressure
What affect does adding heat (Q) or work (W) to a closed system have?
Increases enthalpy/total energy of system
What is the total change in enthalpy from initial to final state independent of?
The path taken
What is a reaction that gives out heat called?
What will the enthalpy of this reaction be?
Exothermic
Negative
What is a reaction that takes up heat called?
Endothermic
What is assumed during thermochemistry?
How is this different to biological reactions?
The reaction is at constant pressure and does no work
Some can convert chemical reactions to work
What are some examples of work being carried out in biological systems?
Mechanical work performed by muscles
Electrical work required to transmit nerve impulses
Chemical work to synthesise molecules (anabolism)
What is the 2nd law of thermodynamics?
When energy is converted from 1 form to another, some of the energy becomes unavailable to do work
E.g. heat energy dissipated into the environment cannot be re-used
What is entropy?
A measure of the disorder or unavailable energy in a system
What alone can drive reaction?
Entropy
What can a change in enthalpy be driven by?
A change in entropy
What does the 2nd law of thermodynamics imply?
Entropy is always increasing
What is free energy?
Energy available to do work at constant temp
In a spontaneous process, what is the free energy change?
What happens?
-ve
Reaction release free energy
What happens if the change in free energy is +ve
Reaction requires free energy
If that energy is NOT provided the reaction doesn’t occur
What does increasing the entropy of protein result in?
Breaking protein –> amino acids
a lot more disorder in single amino acids than a structured protein
What is catabolism?
What change in free energy values does this have?
What type of reaction is this?
Breaking down molecules into small units
-ve
Exergonic (releases energy)
Can be spontaneous
What is anabolism?
What change in free energy value does this have?
What type of reaction is this?
Synthesising complex molecules from their basic constituents
+ve
Endergonic (absorbs heat)
Not spontaneous
Which conditions are stable within biological systems?
Which factor has a major effect on change in free energy?
Temp
Pressure
Conc of components of a reaction
What are the 2 systems adopted to make a reaction proceed in the direction required by an org?
> Alter conc so change in free energy becomes -ve
> Couple reaction w/ a +ve change in free energy value to one w/ a -ve value
–> so that overall the change in free energy is -ve
