Bioenergetics Flashcards
Define Bioenergetics
- transformation and flow of energy within biological systems an their environment
- concerned with the initial and final energy states of reactants (not mechinism nor kinetics)
bio= biology & energetics= energy flow
ie. biochemical thermodynamics
3 components able to flow and interchange within biological systems
What are the 3 major components of Thermodynamcs?
- heat
- energy
- matter
- in the system
System vs Surroundings
- System- part of the universe that we are concerned with
- Surroundings- everythig else
3 types of bioenergetic systems
Isolated vs Closed vs Open Systems
- Isolated- cannot exchange matter or energy w/ its surroundings
- Closed- may exchange energy but not matter w/ the suroundings
- Open- may exchange matter, energy or both w/ the suroundings
There are 2 Laws of Thermodynamics
What is the 1st Law of Thermodynamics?
What does the 1st law of thermodynamics also tell us about energy?
Conservation
the total energy of a system (including suroundings) remain constant
energy can’t be created /destroyed ->converted from one form to another
There are 2 Laws of Thermodynamics
What is the 2nd Law of Thermodynamics?
What does it tell us about the sponteneity of the reaction?
Entropy
Total entropy of a system must increase for a process to occur spontaneously
Entropy is the energy needed for particles to move randomly in the syst.
Energy available to reactants/ products in rxn
What determines how energy flows and whether reactions occur?
determines the feasibility of rxns (direction/ etent)
Gibbs free ebergy (G)
Unit: J/mol
Two forms of G used in chemical reactions
What are the two forms of G and what is the difference?
1.ΔG (change in G of rxn)
2.ΔG° (the std dG-reactants/products @1mol/L)
Difference- ΔG° is only useful under std conditions (1mol/L or reactants/products)
Given a reaction where A ⇆ B (wrt ΔG)
What occurs when the rxn is -ve?
What type of rxn is it? What happens to the energy?
- the rxn is exergonic
- energy is lost from the system
- spontaneous rxn from A–> B
Given a reaction where A ⇆ B (wrt ΔG)
What occurs when the rxn is +ve?
What type of rxn is it? What happens to the energy?
- rxn is endergonic
- energy is required by system from surroundings to occur
- rxn is not spontaneous as it cannot occur on its own
Usually paired w/ exergonic rxns to supply the rxn with energy
Given a reaction where A ⇆ B (wrt ΔG)
What occurs when the rxn equals 0?
What type of rxn is it? What happens to the energy?
- rxn is at equilibrium
- no direction is favoured
Also: ΔG A→B= –ΔG B→A
- spontaneous rxns move towards equilibrium
ΔG is determined by two factors:
What is Enthalpy?
ΔH
Enthalpy and Entropy
change in heat of reactants and products of a rxn
eg. chemical bonds
Neither enthalpy nor entropy can predict rxn feasibility alone!
ΔG is determined by two factors:
What is Entropy?
ΔS
Enthalpy and Entropy
change in the randomness/disorder of reactants and products
Neither enthalpy nor entropy can predict rxn feasibility alone!
What is the equation to determine Gibbs free energy?
with units?
ΔG= ΔH –TΔS
ΔG- J/mol
ΔH- J/mol
T- K (273 + °C)
ΔS- J/mol/K
But free energy can also be defined for ideal gas rxns:
What is the Gibbs free energy equation for ideal gas rxns?
includes the std G
ΔG = ΔG°+ RT ln [B]/[A]
(At constant pressure, absolute T - thermal equilibrium)
Note: ΔG and ΔG°can have different signs
R = gas constant (8.315 J/mol/K)
In = natural logarithm
[B] = concentration of product
[A] = concentration of reactant
