1. Thermodynamics Flashcards
What is the conservation of energy?
energy cannot be created or destroyed
How does entropy work within the laws of thermodynamics?
the disorder of a system always increases
How do living organisms follow the conservation of energy?
they transform energy from one form to another
How do organisms use energy from their environment?
extract useable energy from surroundings and release useless energy back in the form of heat
What happens to the entropy of the universe while transforming energy?
it increases
Define transductions
one thing to another
What state do living organisms exist in?
dynamic steady state
What allows living organisms to transform matter into energy and what do they use?
energy coupling and catalysts
Are living organisms ever at equilibrium with their surroundings?
no
When entropy increases, what is needed to create and maintain order?
work and energy
Define an open system
exchange both energy and matter with surroundings
What type of system are humans?
open system
Define closed system
exchange only energy with surroundings
Define isolated system
cannot exchange energy or matter with surroundings
What is the ultimate source of energy on earth?
sunlight
Define metabolism
sum of all chemical reactions in the cell
Define anabolism
making complex molecules from simpler ones
Does anabolism require or release energy?
require
Define catabolism
breaking down complex molecules into simpler ones
Does catabolism require or release energy?
release
What three quantities define the free energy content of any closed system?
entropy, enthalpy and absolute temperature
Define entropy
randomness or disorder of a system
When disorder increases, how does this affect entropy?
it becomes positive
When disorder decreases, how does this affect entropy?
it becomes negative
Define enthalpy
sum of a system’s internal energy, or heat
When enthalpy (H) is positive, is the equation endothermic or exothermic?
endothermic
When enthalpy (H) is negative, is the equation endothermic or exothermic?
exothermic
Define endothermic
absorb heat energy from surroundings
Define exothermic
release thermal energy to surroundings
What two factors, at a constant temperature, affect the free energy change?
change in enthalpy and entropy
What is the standard free energy change and what symbol is it?
Delta G - constant characteristic for a specific reaction at standard conditions
What are the standard conditions for the free energy change?
temp - 25 C
pressure - 1 atm
reactants - 1M
When delta G^’o is negative, is the reactions exergonic or endergonic?
exergonic
Define exergonic reaction
reaction can occur spontaneously
releases free energy
When Delta G^’o is positive, is the reaction exergonic or endergonic?
endergonic
Define an endergonic reaction
the reaction doesn’t occur spontaneously
requires energy
What do thermodynamic constants, such as delta G^’o show?
where the final equilibrium lies
How do cells carry out endergonic reactions?
coupled to exergonic reactions
When Delta G^’o is negative, what is Keq
> 1
When Delta G^’o is positive, what is Keq?
<1
When Keq is >1, which way does the reaction proceed?
forward
When Keq is <1, which way does the reaction proceed?
reverse
Define energy coupling
chemical coupling of exergonic and endergonic reactions allowing otherwise unfavorable reactions to occur
What does the actual free energy change of a reaction in the cell depend on?
standard change in free energy and actual concentrations of products and reactants
What is the best way to speed up a reaction?
lowering the activation barrier by using catalysts
What do enzymes (catalysts) do?
lower activation energy and raise reaction rate
Define a biochemical pathway
series of related enzyme-catalyzed reactions
Do catalysts alter Delta G?
no
How do catalysts affect the activation free energy?
lower it
Why are pathways controlled?
regulate levels of metabolites
