enzymes and boring stuff

Question 1

role of ATP in energy transfer?

Answer 1

ATP captures and transfers free energy through addition/removal of terminal phosphate group

Question 2

ATP is referred to as an energy ___ molecule. why?

Answer 2

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)

Question 3

why is ATP our “energy currency” for cells?

Answer 3

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)

Question 4

what are catalysts and their functions?

Answer 4

anything that drops the energy of activation of a reaction.

Question 5

are catalysts exclusively enzymes? if not, name another type

Answer 5

no, we can have enzymatic RNA that can act as a catalysts, like ribozymes

Question 6

T/F: catalysts are not changed in a reaction

Answer 6

true

Question 7

does a change in the energy of activation/presence of an enzyme influence ΔG?

Answer 7

no! ΔG remains unchanged regardless of energy of activation

Question 8

do enzymes provide energy in a reaction? if not, then what does?

Answer 8

no!!! reactants and products are what provide energy

Question 9

what is the active site?

Answer 9

area on an enzyme where the R groups of the enzyme interact with the atoms of the substrate

Question 10

describe how an enzyme interacts with a substrate

Answer 10

1. substrate atoms interact with R groups of enzyme’s active site
2. interaction of these atoms causes a strain on a covalent bond; known as transition state
3. as substrate converts into a product, product loses affinity for the enzyme and pops off (never to return O-O)

Question 11

what is induced fit?

Answer 11

enzyme changes the shape of its active site slightly to better fit to the substrate

Question 12

what is acid-base catalysis? does the enzyme permanently change? what does this cause?

Answer 12

involves the transfer of H+/electrons from the substrate. causes a breaking of a covalent bond

Question 13

what is covalent catalysis? does enzyme permanently change?

Answer 13

involves the formation of a temporary covalent bond of a functional group + substrate. no enzyme doesn’t permanently change

Question 14

what is metal ion catalysis?

Answer 14

involves gain/loss of electrons on metals in side chains of enzyme. most common

Question 15

what are prosthetic groups? do they “stay” or “come and go”? example?

Answer 15

lipid derived, organic groups bound to enzyme.
usually stay covalently bound to enzyme
ex. porphyrin ring structure (makes up heme group of hemoglobin)

Question 16

what are cofactors? do they “stay” or “come and go” from enzyme? example?

Answer 16

inorganic ions bound to an enzyme
stay covalently bound to enzyme
ex. iron in center of porphyrin ring

Question 17

what are coenzymes? how do they differ from cofactors or prosthetic groups? example?

Answer 17

usually large organic molecules. “carrying molecules” necessary for capture/donation of energy
difference: don’t permanently bind to enzyme
ex. NADH, FAD

Question 18

which 2 metabolic pathways are universal and fundamental to all cellular life?

Answer 18

glycolysis and citric acid cycle

Question 19

how do cells balance complexities of metabolic pathways?

Answer 19

through regulation of enzymatic activity!

Question 20

how does substrate concentration affect metabolic rate?

Answer 20

more substrate = higher enzymatic rate
(until you reach vmax/point of saturation)
no substrate = no reaction

Question 21

what are inhibitors? what would be a better word to describe them?

Answer 21

molecules that slow the rate of reactions of enzymes, help produce less product
more like “enzyme regulators”

Question 22

4 types of inhibition?

Answer 22

reversible
irreversible
competitive
noncompetitive

Question 23

reversible inhibition?

Answer 23

inhibitor temporarily (and noncovalently) binds to enzyme

Question 24

irreversible inhibition?

Answer 24

inhibitor permanently binds to enzyme (ex. nerve gas which is an irreversible competitive inhibitor)

Question 25

competitive inhibition?

Answer 25

inhibitor binds at active site, “competes” with the substrate for the active site

Question 26

noncompetitive inhibition?

Answer 26

inhibitor does NOT bind at active site but at a different site. changes the shape of the active site and “inactivates” it

Question 27

which type of inhibition do biol systems most rely on?

Answer 27

reversible noncompetitive inhibition
allosteric regulation for instance

Question 28

nerve gas is an example of what type of inhibition?

Answer 28

irreversible, competitive inhibition

Question 29

a type of inhibition common in pharmacology is ___?

Answer 29

reversible, competitive inhibition (making things similar to substrate but reversible so that nothing horrible happens)

Question 30

the site “other than the active site” is referred to as __?

Answer 30

the allosteric regulatory site

Question 31

what is allosteric regulation? is it limited to only inhibition?

Answer 31

interaction of a molecule at an enzyme’s allosteric site that ultimately changes the shape of the enzyme
allosteric regulation can also have ACTIVATOR molecules!

Question 32

what is feedback inhibition?

Answer 32

process by which the end product of a metabolic pathway acts as an allosteric inhibitor by inhibiting an earlier step of its own synthesis pathway!

Question 33

allosteric regulation is a type of ___ inhibition

Answer 33

reversible, noncompetitive inhibition

Question 34

what is covalent modification? an example?

Answer 34

addition or subtraction of a functional group/covalent bond from an enzyme
ex. phosphorylation

Question 35

what are isozymes?

Answer 35

enzymes with the same function but are structurally different/are regulated differently