Day 2 Energy

law of thermodynamics

physical law governing energy transformation

first law of thermodynamics

energy cannot be created or destroyed, only transformed

second law of thermodynamics

every energy transfer/transformation increases the entropy of the universe

free energy (G)

portion of a system’s energy that can do work; reflect a system’s instability. determines whether reaction is spontaneous

spontaneous

process that occurs without an input of energy and results in an increase in entropy (negative G). does not necessarily mean fast

non spontaneous

process that requires an input of energy to proceed (positive G); decreases entropy on its own

endergonic reaction

non spontaneous reaction that requires input of energy; positive G; anabolism

exergonic reaction

spontaneous reaction that releases free energy; negative G; catabolism

positive G

products have more free energy than reactants (endergonic, non spontaneous)

negative G

products have less free energy than reactants (exergonic, spontaneous)

enthalpy (H)

total energy in terms of heat/bond energy; change in enthalpy during a reaction

entropy (S)

measure of disorder/randomness in a system; change in entropy during a reaction. entropy of universe always increases with energy transfer

ATP hydrolysis

breakdown of ATP into ADP+inorganic phosphate (Pi), releasing free energy (-7.3 kcal/mol under standard conditions) that powers cellular work

energy coupling

use of exergonic process (like ATP hydrolysis) to drive endergonic process, allowing cell to do work