BIOL 213- chapter 3: energy, catalysis, and biosynthesis

kinetic energy

energy of motion

potential energy

stored energy from position

work

energy released during transformation

bioenergetics

the study of how energy flows through living organisms

laws of thermodynamics

"rules" that govern aspects of all energy transformations, originally formulated in 19th Century for steam engines, applied (with some mathematical adjustments) to cellular/biochemical conditions

1st law of thermodynamics

energy cannot be created or destroyed, only transformed

2nd law of thermodynamics

every energy transfer or transformation increases the entropy of the universe

entropy

a measure of disorder or randomness, energy not available to do work

Gibbs free energy

identifies amount of energy available for work versus energy lost to entropy; applies to any energy conversion

H = G + TS

G = H - TS

-H = enthalpy; total energy

-S = entropy; energy unavailable for work

-G = Gibbs Free Energy; available for work

delta G

change in free energy, measures the amount of disorder caused by the reaction, also measures how far away the equilibrium a reaction is, equilibrium is reached when the forward and backward reactions occur at equal rates when delta G=0

delta G < 0

reaction is "spontaneous," energy is released as reaction proceeds, exergonic

delta G > 0

reaction is "non-spontaneous," needs energy input to proceed to completion, endergonic

standard free energy change (delta G degree)

represents the gain or loss of free energy as one mole of reactant is converted to one mole of product under "standard conditions"

activation energy

energy that is needed to get a reaction started, does not figure into Gibbs free energy budget, is recovered when reaction proceed

catalysts

speed up chemical reactions by lowering the activation energy of a reaction

enzymes

are biological catalysts (proteins with special abilities to promote specific reactions)

metabolism

collection of biochemical reactions in cell, cooperative action of many different enzymes, many different biochemical reactions, many reactions linked to one another by cofactors

ATP

(adenosine triphosphate) main energy source that cells use for most of their work, energy cofactor

NAD+/NADH

an organic molecule that serves as an electron carrier by being oxidized (losing electrons) to NAD+ and reduced (gaining electrons) to NADH, redox cofactor

coupled reactions

the energy released by an exergonic reaction is used to drive an endergonic reaction