enzymes (for prac prac)

Question 1

enzymes are ____________ molecules which act as ______________ ___________

Answer 1

protein, biological catalysts

Question 2

enzymes greatly __________ rate of a _________ _________ without themselves being __________ at the end of the __________

Answer 2

increase, chemical reaction, changed, reaction

Question 3

enzymes enable ____________ reactions to proceed _________ but at _____ ______

Answer 3

metabolic, rapidly, low temps

Question 4

enzymes are __________ so a single enzyme will generally catalyse …

Answer 4

specific, only a single reaction

Question 5

enzymes serve to _________ the reactions within each metabolic pathway

Answer 5

control

Question 6

most enzymes are _________ _________ and have ________ ______ with a __________ _______ where reaction takes place

Answer 6

globular proteins, active sites, specific shape

Question 7

enzymes
- are effective in _______ amts
- remain chemically __________ at end of reaction
- function by ___________ the ___________ _________ needed for reaction to occur

Answer 7

• small
• unaltered
• lowering, activation energy

Question 8

enzymes are very ____________: most enzyme-catalysed reactions are 10^3 to 10^8 times faster than uncatalysed reactions

Answer 8

efficient

Question 9

enzymes have a ______ degree of ____________
- __________ to __ type of substrate molecule
- __________ to ____ of substrates having _________ ________
- ___________ is due to _______________ at ________ _______

Answer 9

• high, specificity
• specific, 1
• specific, grp, similar shape
• specificity, conformation, active site

Question 10

all enzymes have ________ _________ shape & r relatively _______ molecules

Answer 10

complex globular, large

Question 11

activity of enzymes can be changed by presence of _____________/_____________

Answer 11

inhibitors/activators

Question 12

only _______ _____ of enzyme molecules comes into _________ _________ with substrate

Answer 12

active site, direct contact

Question 13

substrate binds to _______ ______ of enzyme, forming the …

Answer 13

active site, enzyme-substrate complex

Question 14

larger the Ea, _________ the reaction

Answer 14

slower

Question 14

________ of active site _________________ to ________ of substrate

Answer 14

shape, complementary, shape

Question 15

def of activation energy (Ea):

Answer 15

energy needed to make substances react

Question 16

when Ea of reaction lowered, _____ of reaction ___________

Answer 16

rate, increased

Question 17

enzymes serve to _________ activation energy needed for __________ reaction to _______

Answer 17

reduce, chemical, start

Question 18

LOCK & KEY HYPOTHESIS
I. active site has _________ _______ to which substrate binds
II. substrate (key) shape is _____________ to shape of enzyme ________ _____ (lock)
III. shape of substrate fit ________ into shape of _______ _____ to form ________________ _______
IV. once reaction is complete& products r formed, the products ___ _______ ____ into active site & are __________ into surrounding medium, leaving _______ _____ free to _________ _____ substrate molecules

Answer 18

• specific shape
• complementary, active site
• exactly, active site, enzyme-substrate complex
• no longer fit, released, active site, receive new

Question 19

effective collision occurs when substrate ________ at just the right point into enzyme

Answer 19

collides

Question 19

EFFECT OF TEMP ON RATE OF ENZYME REACTION
- increase temp, ___________ in _________ energy of enzyme & substrate molecules, __________ in ___________ of ___________ ___________ between enzyme & substrate molecules –> _____ enzyme-substrate complexes formed per _____ _____
- rate of reaction ____________ with temp until __________ temp
- beyond ___________ temp, rate of reaction ____________ _______ becus enzyme __________

Answer 19

• increase, kinetic, increase, frequency, effective collisions, more, unit time
• increases, optimum
• optimum, decreases rapidly, denatured

Question 20

INDUCED FIT HYPOTHESIS
I. stemmed from evid that some enzymes & their active sites were physically __________ strucs
II. shape of substrate still ________________ to shape of active site
III. binding of substrate to active site __________ ______ _________________ _________ in ________ of __________ –> substrate to ____ more ________ into active site when they form _____________________ ________ –> enzyme performs catalytic func more ____________

Answer 20

• flexible
• complementary
• induces small conformational change, shape, enzyme, fit, snugly, enzyme-substrate complex, effectively

Question 21

FACTORS AFFECTING RATE OF ENZYME ACTION

Answer 21

• temp
• pH
• substrate conc
• enzyme conc

Question 22

EFFECT OF TEMP ON RATE OF ENZYME REACTION
optimum temp is temp at which

Answer 22

enzyme functioning at its max rate

Question 23

EFFECT OF TEMP ON RATE OF ENZYME REACTION - since enzymes are made of ________, excessive _____ disrupts ________________ bonds which __________ the ___________ & _____________ strucs of enzyme causing it to ________ & _________ shape of _______ _____ is _____. - enzyme said to be ___________

Answer 23

- proteins, heat, intramolecular, stabilise, tertiary, quaternary, unfold, precise, active site, lost - denatured

Question 24

enzyme denaturation is usually

Answer 24

irriversible

Question 25

EFFECT OF TEMP ON RATE OF ENZYME REACTION if temp is near/ below freezing pt, enzymes r ___________. enzyme activity is very ____

Answer 25

inactivated, low

Question 26

describe graph of effects of temp on rate of reaction

Answer 26

starting form very low, then increase till optimum temp, then decrease faster than the increase

Question 27

EFFECT OF PH ON RATE OF ENZYME REACTION optimum pH of an enzyme is pH at which

Answer 27

max rate of reaction occurs

Question 28

AT OPTIMUM PH, - ________________ bonds that maintain _________ struc of enzyme r ________ - ______________ of active site is ______ ideal for ___________ _________ - there'll be ________ __________ of __________ __________ between enzyme & substrate molecules --> _________ no. of ___________________ __________ formed per _____ _______

Answer 28

- intramolecular, protein, intact - conformation, most, substrate binding - highest frequency, effective collisions, greatest, enzyme-substrate complexes, unit time

Question 29

EFFECT OF PH ON RATE OF ENZYME REACTION within certain range, effects of Ph normally

Answer 29

reversible

Question 30

EFFECT OF PH ON RATE OF ENZYME REACTION at pH higher/lower than optimum pH, the ___ conc wouldve changed - this _______ bonds that help maintain ______________ of enzyme --> _______ _____ & substrate binding affected

Answer 30

- H+ - alters, conformation, active site

Question 31

EFFECT OF PH ON RATE OF ENZYME REACTION at extreme pH changes, _______________ of enzyme severely ________ --> becomes ___________

Answer 31

conformation, altered, denatured

Question 32

describe graph of effects on pH on rate of reaction

Answer 32

increase till optimum pH, then decrease at abt the same rate as increase

Question 33

EFFECT OF SUBSTRATE CONC ON RATE OF ENZYME REACTION - for fixed enzyme conc, rate of enzyme reaction ___________ with increasing substrate conc

Answer 33

increases

Question 34

EFFECT OF SUBSTRATE CONC ON RATE OF ENZYME REACTION - increase in no. of substrate molecules causes ___________ in ____________ of _________ __________ between enzyme & substrate molecules so _____ enzyme-substrate complexes formed ____ _____ _____ & rate of reaction ____________ - rate of reaction limited by ____________ conc

Answer 34

- increase, frequency, effective collisions, more, per unit time, increased - substrate

Question 35

EFFECT OF SUBSTRATE CONC ON RATE OF ENZYME REACTION there'll be a point where any further increase in substrate conc produces ____ ____________ ________ in rate of reaction due to - ____ ________ _____ of ____ enzyme molecules r ____________ with substrate molecules - any ______ substrate molecule got to _____ until the _____________________ ________ has __________ the __________ b4 it can enter - rate of reaction now _________ by enzyme conc

Answer 35

no significant change - all active sites, all, saturated - extra, wait, enzyme-substrate complex, released, products - limited

Question 36

describe graph of effect of substrate conc on rate of reaction

Answer 36

rate increases as substrate conc increases till enzyme conc is limiting, then the graph becomes like a horizontal line

Question 37

EFFECT OF ENZYME CONC ON RATE OF ENZYME REACTION given that substrate conc maintained at ____ level & pH & temp kept constant, rate of reaction is _______________ to enzyme conc

Answer 37

high, proportional

Question 38

EFFECT OF ENZYME CONC ON RATE OF ENZYME REACTION - as conc increases, ___________ of ___________ ____________ between enzyme & substrate molecules ___________ - _________ no. of enzyme-substrate complexes formed ____ _____ _____

Answer 38

- frequency, effective collisions - greater, per unit time

Question 39

EFFECT OF ENZYME CONC ON RATE OF ENZYME REACTION at very high enzyme concs, if conc of substrate molecules is __________, the increase in enzyme conc _________ result in ____ ________ increase in rate of reaction

Answer 39

limiting, wouldn't, any further

Question 39

describe graph of effect of enzyme conc on rate of reaction

Answer 39

rate increases as enzyme conc increases until substrate is limiting then the graph becomes like a horizontal line