Bio Ch. 8

metabolism

all of an organism’s chemical reactions

metabolic pathway

a specific molecule is catalyzed by an enzyme to produce a product

catabolic pathways

release energy —> break complex molecules into simpler compounds (ex. cell resp)

anabolic pathways

consume energy —> build complex molecules from simpler ones (ex. protein synthesis)

energy

the capacity to cause change

kinetic energy

energy of motion

thermal energy

energy from random movement of atoms/molecules

heat

transfer of thermal energy from one object to another

potential energy

energy based on location & structure

chemical energy

potential energy available for release in a chemical reaction

thermodynamics

study of energy transformations in a collection of matter

1st law of thermodynamics (principle of conservation of energy)

energy cannot be created or destroyed, only transformed

2nd law of thermodynamics

every energy transfer increases the entropy of the universe

entropy

irreversible change of systems through time

free energy

measure of a system’s stability (higher G become stable/lower G)

equilibrium (max. stability)

point at which forward and reverse reactions occur at the same time

exergonic reaction

energy OUT —> spontaneous reaction that releases energy to surroundings

endergonic reaction

energy IN —> absorbs free energy from surroundings (nonspontaneous)

chemical work

use of energy to drive endergonic reactions

transport work

pumping substances across membranes against the direction of spontaneous movement

mechanical work

ex. beating cilia or contracting muscle cells

energy coupling

using an exergonic process to drive an endergonic one

ATP

ribose + adenine + 3 phosphate groups

phosphorylation

transfer of a phosphate group from ATP to another molecule

phosphorylated intermediate

molecule being phosphorylated (increases reactivity & free energy / decreases stability)

catalyst

chemical agent that speeds up a reaction

enzyme

micromolecule that acts as a catalyst

activation energy (E_A)

initial energy needed to break reactant bonds

transition state

molecules become unstable when enough energy is absorbed to break bonds

catalysis

catalyst speeds up a reaction without being consumed by it

substrate

the reactant that an enzyme acts on (most end in -ase)

enzyme-substrate complex

when an enzyme binds to a substrate

active site

region on the enzyme (pocket or groove) that binds to substrate

induced fit

enzyme changes shape after substrate enters active site

cofactors

nonprotein helpers that permanently bond with the enzyme

coenzymes

organic cofactors (ex. vitamins)

competitive inhibitors

look like substrate —> bind to active site & decrease enzyme productivity (countered by increased substrate conc.)

noncompetitive inhibitors

force enzymes to change shape of their active site to become less effective at catalysis

allosteric reaction (in proteins)

regulatory molecules bind to active site & other location to inhibit/stimulate protein function

active allosteric reaction

stabilizes shape of an enzyme w/ functional active sites

inactive allosteric reaction

stabilizes an enzyme’s inactive form (substrate cannot bind)

cooperativity

change of shape in the enzyme that stabilizes active form when substrate binds to an active site

feedback inhibition

end product of a metabolic pathway closes the pathway to prevent chemical resource waste

multienzyme complex

assembly of enzymes work together to catalyze a sequence of reactions