Chapter 8 -- An Introduction to Metabolism

metabolism

totality of an organism's chemical reactions

metabolic pathway

specific molecule altered in a series of steps --> certain product

catabolic pathway

releases energy, large --> small, breakdown

anabolic pathway

consume energy, small --> large, biosynthesis

bioenergetics

how energy flows through living organisms

energy

capacity to cause change

kinetic energy

when moving objects make other objects move and perform work

thermal energy

associated with random movement of atoms/molecules

heat

thermal energy in transfer

potential energy

matter possesses because of its position/structure

chemical energy

energy available for release in a chemical reaction

thermodynamics

study of energy transfers that happen in a collection of matter

isolated system

can't exchange energy or matter outside of itself

open system

can exchange energy or matter outside of itself

firs law of thermodynamics; principle of conservation of energy

energy of the universe is constant

second law of thermodynamics

every energy transfer or transformation increases the entropy of the universe

entropy

measure of molecular disorder; more disorder=more entropy

spontaneous process

contributes to entropy; can proceed without energy input

nonspontaneous process

decreases entropy; needs an energy input

free energy

portion of a system's energy that can do work when pressure and temperature are uniform throughout it

equilibrium

system at lowest possible free energy

exergonic reaction

net release of free energy; change in free energy less than zero, energy outward, spontaneous

endergonic reaction

net release of free energy; absorbs free energy from surroundings; energy inward, nonspontaneous

energy coupling

use of an exergonic process to drive an endergonic one

chemical work

pushing of endergonic reactions

transport work

pumping substances across membranes against direction of spontaneous movement

mechanical work

movement

phosphorylation

transfer of a phosphate group from ATP --> another molecule for chemical work

phosphorylated intermediate

recipient molecule with covalentely bonded phosphate

catalyst

chemical agent that speeds a reaction without being consumed by it

activation energy

energy needed to contort the reactant molecules so the bonds can break

catalysis

where a catalyst speeds up a reactions without being consumed

substrate

reactant an enzyme acts on

enzyme-substrate complex

enzyme binds to its substrate(s)

active site

pocket/groove on enzyme surface where catalysis occurs

induced fit

tightening of enzyme when substrate binds

saturated

when all enzymes have their active sites engaged

cofactors

nonproteins that permanently or loosely bind to enzymes to help in catalytic activity

conenzyme

organic cofactor

enzyme inhibitors

selectively inhibit actiong of specific enzymes

competitive inhibitors

resemble normal substrate and compete for active site admission and make it less effective/stop working

noncompetitive inhibitors

bind to place on the enzyme other than the active site and make it less effective/stop working

allosteric regulation

protein's function at one site affected by binding of a regulatory molecule to another

activator

binding of this allosteric regulator stabilizes the active sites

inhibitor

binding of this allosteric regulator stabilizes the inactive sites

cooperativity

binding of one substrate molecule --> stabilizes the active site

feeback inhibition

metabolic pathways stopped by inhibitory binding of its end product to an enzyme that acts early in the pathway