biothermodynamics Flashcards
chemical rxns and energy
determined by concentration of reactants and products
anabolic
small molecules assemble to form larger molecule
catabolic
large molecules are broken into smaller molecules
exergonic
free energy is released
spontaneous with -G
endergonic
free energy is absorbed
nonspontaneous +G
ATP hydrolysis is exergonic or endergonic?
exergonic»_space; then facilitates endergonic rxns
kinetic energy
energy in motion
potential energy
stored energy
i.e. glycogen
structure of enzymes
most are proteins but some enzymes are made of RNA (ribozymes)
active site
area of the enzyme where the substrate binds
allosteric site
secondary location where an effector binds
effectors can be activators or inhibitors
mechanism of rxns (for enzymes)
- substrate (reactant) enters the active site of the enzyme
- enzyme and substrate change shape slightly to better catalyze the reaction - forms the enzyme-substrate complex
- enzyme facilitates the rxn by lowering the activation energy
- products are released and the cycle repeats
enzyme function
act as catalysts by lowering activation energy needed for a reaction
what does lowering the activation energy do the rxn
increases rate of the rxn / makes it go faster
characteristics of enzyme function:
- substrate specific
- enzymes are unchanged by the rxn
- catalyze forward + reverse rxns
- have varying function depending on pH and temp
- have an active site that binds substrates via induced fit
competitive inhibition
substance that mimics the substrate inhibits enzyme by binding to active site thus preventing binding of substrate
how to overcome competitive inhibition?
increasing substrate concentration
what happens to Km and Vmax with competitive inhibition
Km increases
Vmax stays the same
noncompetitive inhibition
substance inhibits the enzyme by binding to a secondary location called the allosteric site
substrate can still bind but the inhibitor prevents rxn
what happens to Km and Vmax with noncompetitive inhibition
Km stays the same
Vmax decreases
ATP
source of chemical energy
stores energy generated from the exergonic rxns in the ETC that can then be used to fuel endergonic rxns
how is ATP formed
phosphorylation - which creates energy rich triphosphate bond (ATP formation is endergonic)
how is ATP broken apart
hydrolysis - releases energy and phosphate (ATP hydrolysis is exergonic)
what is Vmax
maximum velocity of the rxn at peak substrate saturation
what is Km
substrate concentration at which the rate of the rxn is half of the max velocity
what does Km inversely represent
binding affinity
