BI220 - Bioenergetics

metabolism

sum of the chemical reactions in an organism

• involve many intricate, multi-step pathways

• require, release, store, and transfer energy

anabolic reaction

simple → complex

• dehydration

• store energy

catabolic reaction

complex → simple

• hydrolysis

• release energy

energy

capacity to do work

• development, growth, repair, reproduction

kinetic energy

energy of motion

• thermal

• electrical

potential energy

stored energy

• chemical

• nuclear

what kind of bonds have more potential energy

weak bonds (hydrogen, nonpolar interactions)

• atoms less stable

thermodynamic system

collection of matter

• total energy conserved

• initial energy = final energy

first law of thermodynamics

energy cannot be created nor destroyed

• only transformed

what is an unusable form of energy

heat

• cannot be converted to mechanical work

second law of thermodynamics

every energy transformation increases entropy

• net result must increase amount of entropy

entropy

disorder

what kinds of reactions are found throughout the energy system

complementary sets

• photosynthesis and cellular respiration

spontaneous process

• occur without energy input

  • quick/slow

  • exergonic

  • increase entropy

non-spontaneous process

• requires energy input

  • quick/slow

  • endergonic

  • decrease entropy

Gibbs free energy

net energy associated w/ a reaction that is available to do work

• products-reactants

equilibrium

optimal stability

• G=0

ATP and GTP

chemical coenzymes used by cell

• store energy generated through catabolic reactions

NADH, NADPH, FADH2

coenzymes that carry high energy e-

• provide energy for photosynthesis/cellular respiration

energy coupling

linking exergonic and endergonic reactions

• energy provided by exergonic reaction fuels endergonic reaction

mechanical work

using energy to physically change the shape of cell/protein

• muscle contractions, movement of motor proteins

transport work

using energy to pump substances cross a membrane

• sodium and potassium ions

chemical work

synthesizing polymers

energy stored in atp

a LOT of free energy between phosphate bonds

ATP hydrolysis

G = -7.3 kcal/mol

what facilitates coupling of ATP hydrolysis with endergonic reactions

transfer of phosphate group

why don’t we run out of ATP

recycled

activation energy

initial input of energy to facilitate start of reaction

• breaking of bonds → form new ones

enzymes

catalyst

• accelerate chemical reaction w/o being changed