Energy, Thermodynamics, and Enzyme Function

energy

the ability to do work

kinetic energy

energy of motion

potential energy

stored energy (ex: concentration gradient)

1st law of thermodynamics

energy is conserved. It can be transferred or transformed but never destroyed

2nd law of thermodynamics

in every energy transfer or transformation increases the disorder of the universe

free energy

energy that is available to do work

formula for free energy

G = H - TS

H in free energy equation

enthalpy of total energy in a system

T in free energy equation

temperature (measure of kinetic energy)

S in free energy equation

entropy (unavailable energy)

endergonic reactions

require energy, has positive ΔG and are not spontaneous

exergonic reactions

release energy, has a negative ΔG (free energy decreased) and are spontaneous

energy profile of a spontaneous reaction

overall a negative ΔG and is exergonic since spontaneous reaction is releasing energy

activation energy

some energy is required to get the reaction started

transition state

the activation energy that makes the curve go up

function of enzymes

Enzymes lower the activation energy required for an action to occur.

catalytic cycle of an enzyme

is the reaction of the enzyme (steps of it)

enzyme specificity

the enzyme interacts with specific substrates so it has a specific shape and feature

substrate concentration effect on reaction rate

Higher substrate concentration = higher rate of reaction

factors affecting enzyme activity

temperature, pH, inhibitors (noncompetitive & competitive), substrate concentration, coenzymes

temperature effect on enzymes

can denature enzymes and affect function

pH effect on enzymes

can reduce activity because reduces speed of reaction if not optimal pH

coenzymes

needs both coenzymes to catalyze reaction

inhibitors

non-competitive can make less functional enzymes and competitive can change the rate of reaction