BIOL Ex 2B - Metabolism

Zanzot - Metabolism Expanded

metabolism

totality of an organism’s chemical reactions

metabolic pathway

begins w/ a specific molecule & ends w/ a product

each step catalyzed by an enzyme

catabolism

breaks down complex molecules into simpler compounds to release energy

e.g hydrolysis, cellular respiration

anabolism

uses energy to build complex molecules from simpler ones

e.g. synthesis of proteins from amino acids

bioenergetics

study of how organisms manage their energy resources

thermodynamics

study of energy transformations

energy

the capacity to cause change/do work

potential energy

stored energy, has high instability

first law of thermodynamics

energy is constant, cannot be created/destroyed

second law of thermodynamics

energy transfer is NOT 100% efficient

spontaneous processes (-ΔG)

changes that occur w/o energy input

must increase entropy of the universe

can only do work when working to equilibrium

since they are open systems, cells decrease entropy in themselves but increase entropy in the universe

how organisms create order within themselves while increasing entropy

free energy (G)

measure of a system’s instability

tendency to change to more stable state

energy that can do work when temp. and pressure are uniform (cell)

exergonic reactions

products < reactant

spontaneous

-ΔG (energy release)

graph? (products & reactants)

endergonic reactions

non-spontaneous

+ΔG (req/absorbs energy)

products > reactant

catabolic pathways

metabolism evades equilibrium through ___ ___ that release free energy

energy coupling

uses an exergonic process to drive an endergonic one

catalyst

chem. agent that speeds up a reaction w/o being consumed by the reaction

enzyme

catalytic protein

substrate

reactant acted on by an enzyme

activation energy E_A

initial energy needed to start a chemical reaction

enzyme-substrate complex

bond from an enzyme bonding to its substrate

active site

region on the enzyme where the substrate binds

induced fit

ex: a substrate brings chem. groups of the active site into positions that enhance their ability to catalyze the reaction

different optimal conditions (pH, temp)

every enzyme has different ___ ___ for activity

cofactors

non-protein enzyme helpers (inorganic)

coenzymes

non-protein enzyme helpers (organic, vitamins)

competitive inhibitors

bind to the active site of an enzyme

competing w/ the substrate

noncompetitive inhibitors

bind to another part of an enzyme (away from active site)

causes enzyme to change shape & make the active site less effective

protein inhibitors

competitive and noncompetitive

ex: drugs, make enzymes less effective

allosteric regulation

inhibits or activates enzyme activity

occurs when a molecule binds to a protein at one site and affects the protein’s fx at another site

cooperativity

ex: a substrate will bond to an inactive enzyme & make it active now for others (in Hb)

feedback (loop) inhibition

regulates metabolic pathway to make more needed product (positive fb) or to stop making product (negative fb) to save resources

anchoring enzymes w/ similar fx together and managing their energy budget

cells make pathways more efficient by

• orienting substrates correctly

• straining substrate bonds

• providing favorable environment (pH, temp.)

• covalently bonding to substrate

how active sites lower the E_A barrier (4)

2 (acidic)

optimal pH for pepsin (stomach enzyme)

8 (basic)

optimal pH for trypsin (intestinal enzyme)