enzymes and boring stuff Flashcards
(35 cards)
role of ATP in energy transfer?
ATP captures and transfers free energy through addition/removal of terminal phosphate group
ATP is referred to as an energy ___ molecule. why?
formation of ATP from ADP is used to drive the formation of ADP from ATP.
endergonic and exergonic reactions here are coupled! (the energy from one reaction is used to drive another reaction, a cycle)
why is ATP our “energy currency” for cells?
covalent bond formed at the terminal phosphate group is very weak, making it easy and convenient to go from ADP/AMP to ATP (doesn’t take lots of energy)
what are catalysts and their functions?
anything that drops the energy of activation of a reaction.
are catalysts exclusively enzymes? if not, name another type
no, we can have enzymatic RNA that can act as a catalysts, like ribozymes
T/F: catalysts are not changed in a reaction
true
does a change in the energy of activation/presence of an enzyme influence ΔG?
no! ΔG remains unchanged regardless of energy of activation
do enzymes provide energy in a reaction? if not, then what does?
no!!! reactants and products are what provide energy
what is the active site?
area on an enzyme where the R groups of the enzyme interact with the atoms of the substrate
describe how an enzyme interacts with a substrate
- substrate atoms interact with R groups of enzyme’s active site
- interaction of these atoms causes a strain on a covalent bond; known as transition state
- as substrate converts into a product, product loses affinity for the enzyme and pops off (never to return O-O)
what is induced fit?
enzyme changes the shape of its active site slightly to better fit to the substrate
what is acid-base catalysis? does the enzyme permanently change? what does this cause?
involves the transfer of H+/electrons from the substrate. causes a breaking of a covalent bond
what is covalent catalysis? does enzyme permanently change?
involves the formation of a temporary covalent bond of a functional group + substrate. no enzyme doesn’t permanently change
what is metal ion catalysis?
involves gain/loss of electrons on metals in side chains of enzyme. most common
what are prosthetic groups? do they “stay” or “come and go”? example?
lipid derived, organic groups bound to enzyme.
usually stay covalently bound to enzyme
ex. porphyrin ring structure (makes up heme group of hemoglobin)
what are cofactors? do they “stay” or “come and go” from enzyme? example?
inorganic ions bound to an enzyme
stay covalently bound to enzyme
ex. iron in center of porphyrin ring
what are coenzymes? how do they differ from cofactors or prosthetic groups? example?
usually large organic molecules. “carrying molecules” necessary for capture/donation of energy
difference: don’t permanently bind to enzyme
ex. NADH, FAD
which 2 metabolic pathways are universal and fundamental to all cellular life?
glycolysis and citric acid cycle
how do cells balance complexities of metabolic pathways?
through regulation of enzymatic activity!
how does substrate concentration affect metabolic rate?
more substrate = higher enzymatic rate
(until you reach vmax/point of saturation)
no substrate = no reaction
what are inhibitors? what would be a better word to describe them?
molecules that slow the rate of reactions of enzymes, help produce less product
more like “enzyme regulators”
4 types of inhibition?
reversible
irreversible
competitive
noncompetitive
reversible inhibition?
inhibitor temporarily (and noncovalently) binds to enzyme
irreversible inhibition?
inhibitor permanently binds to enzyme (ex. nerve gas which is an irreversible competitive inhibitor)
