C1: Biochemistry General Concepts (Ch. 3) Flashcards
Class 1
what is the first law of thermodynamics?
implies that when the energy of a system decreases, the energy of the rest of the universe must increase and vice versa
what is the second law of thermodynamics?
the disorder or entropy of the universe tends to increase
what is the symbol for entropy?
S
what is exergonic/ endergonic?
exergonic is when energy exits the system, endergonic when energy is added
what is activation energy?
the energy required to allow a rxn to proceed
what is reaction coupling?
one very favorable rxn is used to drive an unfavorable one
what is an active site?
the region in an enzymes 3D structure that is directly involved in catalysis
what are substrates?
the reactants in an enzyme- catalyzed rxn
enzymes catalyze rxns by binding substrates at the active site which generates a ________ ________ and then _______ are released.
transition state, products
what can enzymes be allosterically controlled by?
small molecules such as ADP
how are transition states stabilized?
in the active site of enzymes by electrostatic interactions
what is allosteric regulation?
the modification of active site activity via interactions of molecules w other sites on the enzyme (called allosteric sites)
what is negative feedback?
when an end product shuts off an enzyme too early in the pathway
what is gibbs free energy?
- when is gibbs free energy negative? what does this mean in terms of spontanity?
- when is it positive?
- the difference in energy between reactants and products
- GFE is negative when the products have less energy than the reactants and the rxn is spontaneous
- opp. of when its negative
what is the formula for gibbs free energy?
change in G = change in H - T * change in S
what is a holoenzyme?
the entire enzyme (enzyme and protein)
what is an apoenzyme?
the protein component of an enzyme
what is a cofactor?
- what are organic cofactors AKA?
inorganic or organic elements that are required for enzymatic activity
- coenzymes
in addition to helping enzymes catalyze a rxn, what else do cofactors do?
they are vitamins that are required in biochemical rxns
what is a metalloenzyme?
entire enzyme (enzyme and protein) when a metal ion is associated
what is an irreversible inhibitor?
- are they endergonic or exergonic?
inhibition that cannot be overcome, typically bind to a site on an enzyme (either active or allosteric) and destroy the enzymes ability to catalyze rxns
- exergonic
what is a non- reversible inhibitor?
can bind at a site other than the active site
what is a competitive inhibitor?
compete w the substrate for binding at the active site and can be overcome by addition of more substrate
what is a noncompetitive inhibitor?
binds at allosteric site, does not compete w substrates for binding at the active site
what are uncompetitive inhibitors?
bind to the enzyme- substrate complex, not to the enzyme itself
what is Vmax determined by?
the enzyme and its concentration
what is a non- competitive inhibitors relationship w Vmax?
has a reduced Vmax on a graph in comparison w the normal curve
what is Km?
the amount of substrate required to get 1/2 Vmax
an enzyme functions by…
lowering the activation energy barrier, allowing the rxn to occur more rapidly
what is an enzymes relationship to water?
most require a certain amount of water (usually small) to be functional
a reaction w a low energy of activation will proceed…
more quickly than one w a high energy of activation
what is a catalysts relationship w spontaneous/ nonspontaneous rxns?
a catalyst cannot complete a non spontaneous rxn, all it can do is make a spontaneous rxn faster
what is enzymatic activity regulated by?
phosphorylation or associations w other molecules
what is proteolytic cleavage?
it destroys the enzyme
what ion is necessary for all rxns involving ATP?
Mg^2+
each of the following releases the same amount of energy after hydrolysis of one high-energy bond except one. which one is the exception?
a. ATP
b. dATP
c. UTP
d. ADP
e. AMP
AMP
