Enzyme Mechanisms

Question 1

enzyme

Answer 1

biological catalyst that speed up rates of reaction that would otherwise be too slow to support life

Question 2

catalyst

Answer 2

a chemical agent that changes the rate of reaction without being consumed by the reaction

Question 3

substrate

Answer 3

reactant that enzyme acts on

Question 4

active site

Answer 4

a pocket where the substrate binds - catalytic center where substrate is converted to product

Question 5

where do enzymes act on substrates?

Answer 5

at their active site

Question 6

what are enzymes composed of?

Answer 6

proteins (except 1) - ribozyme

Question 7

how many reactions can an enzyme catalyze?

Answer 7

JUST ONE they are reaction specific

Question 8

metabollic enzymes work in which direction?

Answer 8

most work both BOTH - forward and reverse

Question 9

what does it mean to be substrate specific?

Answer 9

an enzyme can recognize one specific set of substrates related to the reaction it catalyzes

Question 10

An enzyme can only act on one substrate but substrates can have multiple enzymes that react on it

Question 11

what are the main types of enzymes?

Answer 11

simple, complex

Question 12

what are the states of complex enzymes?

Answer 12

apoenzyme, holoenzyme

Question 13

simple enzyme

Answer 13

composed only of protein component

Question 14

complex enzyme

Answer 14

an enzyme that requires a cofactor to function in addition to its protein component

Question 15

apoenzyme

Answer 15

inactive form of the enzyme because it is missing the cofactor

Question 16

holoenzyme

Answer 16

active form of the enzyme with the cofactor

Question 17

types of cofactors

Answer 17

inorganic, organic

Question 18

examples of inorganic cofactors

Answer 18

metal ions, zinc, iron, copper

Question 19

examples of organic cofactors

Answer 19

usually from vitamins of their derivatives

Question 20

prosthetic group organic cofactor

Answer 20

covalently/permanently bonded to an apoenzyme

Question 21

coenzyme organic cofactor

Answer 21

non-covenlently/reversibly bound to an apoenzyme

Question 22

function of oxidereductase

Answer 22

shuffling electrons

Question 23

function of transferase

Answer 23

moving chemical groups

Question 24

function of hydrolase

Answer 24

breaking molecules with water

Question 25

functions of lyase

Answer 25

breaking molecules without water

Question 26

function of isomerase

Answer 26

changine molecular shapre (keeps the same atoms)

Question 27

function of ligase

Answer 27

forming bonds between molecules

Question 28

enzyme name ending

Answer 28

ase

Question 29

what is the induced fit model?

Answer 29

as the substrate binds, the enzyme changes shape leading to a tighter fit bringing chemical groups in position to catalyze the reaction

binding of a substrate induces a favourable change in the shape o the active site

Question 30

exergonic reaction

Answer 30

exothermic - a reaction that releases energy

Question 31

activation energy

Answer 31

amount of energy needed to push the reactants over an energy barrier

Question 32

how do enzymes speed up a reaction?

Answer 32

lower the activation energy

Question 33

what are the mechanisms for lowering activation energy?

Answer 33

1. proximity
2. bond strain
3. microenvironment
4. covalent catalysis

Question 34

proximity & orientation description

Answer 34

active site brings reactants closer together and in the correct orientation

Question 35

bond strain description

Answer 35

active site bends bonds in substrate making it easier to break

Question 36

microenvironment description

Answer 36

creates a favourable environment for the reaction

Question 37

covalent catalysis description

Answer 37

enzymes may bind covalently to substrates in an intermediate step before returning to normal

Question 38

how does covalent catalysis increase reactionr rate

Answer 38

properly orienting the susbtrate, changing the chemistry at the active site

Question 39

limitations to enzyme activity

Answer 39

substrate concentration
temperature
pH
availability of cofactors

Question 40

what is the correlation between substrate concentration and rate

Answer 40

direct, increase in concentration, increase speed of binding to active sites, increased reaction rate

Question 41

what happens with enzyme saturation

Answer 41

active sites on all enzymes are engaged only way to increase productivity is to increase number of enzymes

Question 42

increased temperature effects on enzyme activity

Answer 42

increased temp, increases speef of molecules, incrases collisions between substrate and active site