Biology Chapter 2: Enzymes

Front 1

endothermic rxn

Back 1

requires energy to progress
-final state is higher than the initial state

Front 2

exothermic

Back 2

releases energy in transition
-final state is lower in energy than the initial state

Front 3

enzymes do/not alter overall enthalpy(/\H) for a rxn

Back 3

do not

Front 4

enzymes do/not alter the equilibrium if a reaction

Back 4

do not

Front 5

enzymes do/not affect the rate of the reaction

Back 5

do

ex) catalysts!

Front 6

enzymes are un/changed by the reaction

Back 6

unchanged

Front 7

enzymes in/decrease activation energy

Back 7

decrease

Front 8

enzymes tend to catalyze a single reaction or class of reactions

Back 8

know

Front 9

active site is...

Back 9

location within enzyme where substrate held

Front 10

lock and key method...

Back 10

specific substrate-to-enzyme interaction

Front 11

induced fit theory

Back 11

change of conformation for both the substrate and the active site

Front 12

enzymes...
1. ___ activation energy
2. ___ rate of rxn
3. do/not alter EQ of rxn
4. are/not consumed in rxn
5. are/not pH and temp. specific
6. do/not alter /\G
7. are/not specific

Back 12

1. decrease activation energy
2. increase rate of rxn
3. do not alter EQ of rxn
4. are not consumed in rxn
5. are pH and temp. specific
6. do not alter /\G
7. are specific

Front 13

cofactors

Back 13

non protein molecules

Front 14

apoenzymes

Back 14

enzymes without cofactors

Front 15

holoenzymes

Back 15

enzymes with cofactors

Front 16

prosthetic groups

Back 16

cofactors tightly bound to enzymes

Front 17

two types of cofactors...

Back 17

small metal ions
small organic groups

Front 18

coenzymes

Back 18

= organic cofactors; loosely bound

Front 19

enzyme kinetics affected by...

Back 19

1. concentration
2. temperature
3. pH

Front 20

concentration effects

Back 20

increase number of substrates = decrease in productivity...reaches saturation...

however, increase enzyme number, then capable of taking on more substrate...

Front 21

concentration is dependent upon....

Back 21

[substrate] and [enzyme]

Front 22

saturation

Back 22

max level of productivity...dependent upon [enzyme]

Front 23

Km =

Back 23

affinity...a lower Km means higher affinity for substrate

a high Km means low affinity for substrate

Front 24

1/2Vmax =

Back 24

point where half the enzyme's active sites are full

Front 25

effects of temperature

Back 25

enzymes are most efficient at 37Degrees

-enzymes denature at higher temperatures

Front 26

effects of pH
pH of 7.4 =
pH of 8.5 =
pH of 2 =

Back 26

human optimal pH = 7.2
pH of 7.4 = human blood
pH of 8.5 = pancreas
pH of 2 = pepsin of stomach

Front 27

allosteric effects

Back 27

enzymes that are allosteric means they have multiple binding sites

Front 28

allosteric enzymes have two forms...

Back 28

active
inactive

Front 29

inactive form is...

Back 29

incapable of carrying out enzymatic reaction

Front 30

allosteric activators or inhibitors can bind to the allosteric site

Back 30

know

Front 31

binding to allosteric site causes a ....

Back 31

conformational change in protein

Front 32

activator makes the enzyme...

Back 32

active site more available

Front 33

inhibitor makes the enzyme...

Back 33

active site less available

Front 34

binding to allosteric site might alter the affinity also

Back 34

ex) O2 and hemoglobin

each binding O2 increases affinity...

Front 35

inhibition

Back 35

type of regulation

Front 36

feedback inhibition

Back 36

product may bind to an enzyme or enzzymes earlier on in chain of events; makes enzymes unavailable for other substrates

Front 37

reversible inhibition...3 types

Back 37

3 types...
1. competitive
2. non competitive
3. uncompetitive

Front 38

competitive inhibition
-overcome...how?

Back 38

compete for binding sites...
can be overcome by addition of substrates > inhibiting molecules

Front 39

non competitive inhibition

-overcome? y/n?

Back 39

inhibitor binds to allosteric site and is not in competition for binding site...
can not be overcome by increased substrate concentration

Front 40

non competitive inhibition is inhibiting since...

Back 40

allosteric binding alters the conformational shape of the enzyme

Front 41

irreversible inhibition

Back 41

active site is permanently unavailable or enzyme permanently altered

Front 42

inactive enzymes

Back 42

zymogens

Front 43

zymogens contain a catalytic(active) domain and a regulatory domain

Back 43

regulatory domain must be removed or altered to expose active site