FUN6/Enzymes

Question 1

enzymes are very ________. they only bind to one or a few substrates.

Answer 1

specific

Question 2

each enzymes catalyses _____ reaction type

Answer 2

one

Question 3

some enzymes need ______ to work

Answer 3

cofactors

Question 4

an enzyme is lined with ________ that bind the substrate _________

Answer 4

amino acid side chains, non-covalently

Question 5

when a substrate attaches onto an enzyme, it forms the ________

Answer 5

enzyme-substrate [ES] complex

Question 6

T* is the ___________, a high energy intermediate

Answer 6

transition state

Question 7

the free energy of activation is the difference in energy b/w ____ and ___

Answer 7

A, T*

Question 8

the rate of rxn is determined by the number of ___________ that have enough energy to get over the barrier

Answer 8

substrate molecules

Question 9

enzymes provide alternative reaction pathways that _______ the free energy of activation/activation energy

Answer 9

lower

Question 10

enzymes do not change the free energy of the substrate or the product, they only change the free energy of _________. therefore enzymes do not change the ____ of the rxn.

Answer 10

activation, equilibrium

Question 11

enzymes provide an alternative rxn pathway by means of their ______

Answer 11

active site

Question 12

what are the 2 mechanism of how an active site provide an alternative rxn pathway?

Answer 12

geometric complimentarity/transition state stabilization, electronic complimentarity

Question 13

what is geometric complimentarity?

Answer 13

the active site forces the substrate(s) to bind in a config. that resembles T* (the ES complex)

Question 14

in electronic complimentarity the ___________ can donate/accept protons to forms a stable covalent ES complex

Answer 14

amino acid side chains lining the active site

Question 15

kinases _____ phosphates and phosphatases ______ phosphates

Answer 15

add, remove

Question 16

what do oxideoreductases do?

Answer 16

oxidation reduction reactions

Question 17

what do transferases do?

Answer 17

transfer functional groups

Question 18

what do hydrolases do?

Answer 18

cleave bonds by the addition of water

Question 19

what do lyases/synthases do?

Answer 19

they cleave CC, CS, and CN bonds, often forming a new double bond

Question 20

what do isomerases do?

Answer 20

interconversion of isomers

Question 21

what do ligases/synthetases do?

Answer 21

catalyse bond formation

Question 22

some enzymes require ____ for their activity

Answer 22

cofactors

Question 23

cofactors are _____, while coenzymes are ________

Answer 23

metal ions, organic molecules

Question 24

an apoenzyme is an enzyme _______ a cofactor and a holoenzyme is an enzyme ______ a cofactor

Answer 24

without, with

Question 25

what are the 3 factors that affect rxn rate?

Question 26

each enzyme has an __________ temperature and pH for its biological activity

Answer 26

optimum

Question 27

\_\_\_\_\_\_\_\_ increases with tempertature up to a point, but then decreases due to \_\_\_\_\_\_\_\_\_\_

Answer 27

velocity, denaturation

Question 28

when the pH of an enzyme is outside of the enzymes optimum range, it may affect the function of the ________ or cause \_\_\_\_\_\_\_\_

Answer 28

the amino acid side chains in the active site, denaturation

Question 29

rate/velocity is the number of ________ converted into _____ per unit time

Answer 29

substrate molecules, product

Question 30

rate increases when substrate concentration increases until it reaches \_\_\_\_\_\_\_\_.

Answer 30

maximum velocity

Question 31

most enzymes have a _________ curve

Answer 31

hyperbolic kinetic

Question 32

michealis constant (ksubm) describes how _______ varies with \_\_\_\_\_\_

Answer 32

reaction velocity, substrate conc.

Question 33

ksubm is the ________ that gives Vmax/2

Answer 33

substrate conc.

Question 34

a small Ksubm means that there is a ________ affinity of enzyme for its substrate. a high Ksubm means that there is a ________ affinity of enzyme for its substrate.

Answer 34

high, low

Question 35

a small Ksubm means that there is a __________ turnover rate

Answer 35

quick

Question 36

a high Ksubm means that a higher ____ is required to reach its Vmax

Answer 36

substrate conc.

Question 37

what is a lineweaver-burk plot?

Answer 37

it is the reciprocal of the initial rate ( 1/V0 ) against the reciprocal of the substrate concentration ( 1/[S] )

Question 38

equation of lineweaver-burk plot

Answer 38

Question 39

hexokinase is an enzyme that phosphorylates _______ sugars

Answer 39

hexose, 6 CARBON SUGARS

Question 40

an inhibitor is a substance that can diminish the ________ of an enzyme-catalyzed rxn.

Answer 40

velocity

Question 41

2 types of inhibitors

Answer 41

reversible and irreversible

Question 42

a reversible inhibitor binds to the enzyme via ____ bonds

Answer 42

non-covalent

Question 43

when a reversible inhibitor is used, the ENZYME-INHIBITOR complex can \_\_\_\_\_\_\_. dissociation can occur and enzyme activity can restart.

Answer 43

dilution/dissociate/go away

Question 44

an irreversible inhibitor is when a __________ bond forms. then the enzyme _______ regain activity.

Answer 44

covalent, cannot

Question 45

ex. of irreversible inhibitors

Answer 45

neurotoxic insecticides, aspirin

Question 46

be able to interpret this chart for competitive inhibition.

Answer 46

Question 47

be able to interpret this chart for non-competitive inhibition.

Answer 47

Question 48

what are the 3 types of enzyme regulation

Answer 48

phosphorylation/dephosphorylation, induction & repression of enzyme synthesis, allosteric regulation

Question 49

depending on the enzyme, the phosphorylated form may be _____ or ___ active

Answer 49

more or less

Question 50

allosteric regulation is the regulation of enzyme activity by binding small molecules to sites on the subunit \_\_\_\_\_\_\_\_\_\_

Answer 50

other than the catalytic/ACTIVE site

Question 51

the small molecules in allosteric regulation are called _____ and can have a ______ or _____ effect.

Answer 51

effectors, positive or negative

Question 52

a homotropic effector is \_\_\_\_\_\_\_\_\_\_. a heterotrophic substrate is \_\_\_\_\_\_\_\_\_\_\_

Answer 52

the substrate itself, different from the substrate

Question 53

when there is a homotropic effector, the presence of a substrate at one site enhances catalytic properties of \_\_\_\_\_\_\_\_\_\_\_

Answer 53

other substrate binding sites

Question 54

an ex. of heterotrophic effectors is when the final product of a metabolic pathwat acts as a \_\_\_\_\_\_\_\_\_\_\_\_\_.

Answer 54

negative effector -\> feedback inhibition

Question 55

an example of an heterotrophic effector is \_\_\_\_\_\_\_\_\_\_. it acts as a positive effector.

Answer 55

cofactor binding