Chapter 5 Flashcards
What are the energy sources for cells
Sun and oxidizable organic molecules (carbs, fats, proteins)
What are the 6 kinds of biological work
Synthetic, mechanical, concentration, electrical, heat, and bioluminescence
what is the difference between an open and closed system
an open one can exchange energy (heat or work) with its surroundings
What are thermodynamics
governs flow of energy through a cell
what is the first law of thermodynamics
conservation of energy
energy cannot be created or destroyed, it may be changed from one form to another
what is an exergonic reaction
final state is less than initial state
energy is released
Enthalpy
measure of energy in a thermodynamic system
^H
what is an endergonic reaction
Final state is greater than initial state
input of energey
Which kind of reaction has a positive ^H
Endergonic
During photosynthesis, what form of energy is utilized and what is it converted to
Utilized: light
Converted: light, heat, chemical
During respiration, what forms of energy are created
Chemical and heat
What is the second law of thermodynamics
law of spontaneity
any system tends to spontaneously increase in entropy
Entropy
Measure of randomness (disorder)
^S
When ^S > 0, indicates disorder
Are naturally occurring processes are exergonic or endergonic
Exergonic, because it doesn’t require the input of energy
As the system becomes more random, what happens to the change in ^S
^S becomes less
What is Gibbs Free Energy
^G
measure of the spontaneity of a reaction
tells us if a reaction is thermodynamically feasible (that it can go, not that it will go)
What is the equation for Gibbs Free Energy
^G = ^H - T x ^S
what is the equation for enthalpy
^H = Hproducts - Hreactants
What does it mean when ^G < 0
the reaction can occur spontaneously (it’s exergonic)
What two factors must occur for the reaction to be able to occur
^G being negative and the availability of a pathway
Keq
equilibrium constant
At 25C for reactions that are reversible
it is the ratio of product concentration to reactant concentration
What is the equation for the equilibrium constant
Keq = [product]eq / [reactant]eq
How does ^G compare to Keq
^G is lowest at equilibrium and higher the further you deviate
When the stuff is at chemical equilibrium, what will the Keq be
1.0
So what happens if concentration ratio is greater than 1
reaction goes to the left because it needs to produce more reactants
What happens if concentration ratio is less than 1
reaction goes to the right to produce more products
what are the standard conditions
at 25C, 1 atm pressure, pH=7, all products and reactants at 1 mole L-1
what is the difference between ^G0’ and ^G’
the first one is at standard conditions and the second is at normal cellular conditions and pH=7
what does it mean when ^G’ is positive
need to supply energy and a pathway
what does it mean when ^G’=0
no work done so no energy required
Keq=1 at equilibrium
equation for ^G0’
^G0’ = -R T Ln(K’eq)
What does pr stand for
prevailing conditions
equation for ^G’
^G’ = ^G0’ + R T Ln([products]pr / [reactants]pr)
what is the gas constant
R= 1.987
what is the T going to be at standard conditions
298K
what is the meaning of the relationship between ^G0’ and K’eq
indicates how far from equilibrium the reaction lies
What is the relationship between ^G0’ and K’eq
inverse
K’eq=1, ^G=0
What is a steady state
where cells usually maintain themselves through which matter is flowing. it is not equilibrium because then the cell would stop having reactions
Why is the ^G’ for ATP and underestimate
because of nonstandard conditions
