many proteins are enzymes

Question 1

how do enxymes act as biological catalysts

Answer 1

each enzymes lowers activation energy
to speed up rate of reaction

Question 2

what type of reactions do enzymes catalyse

Answer 2

intracellular and extracellular that determine structures and functions from celllular to whole organism level

Question 3

describe the induced fit model of enzymes action

Answer 3

1. substrate binds to active site
2. causing active site to change shape so its complementary to substrate
3. so enzyme-substrate complex forms
4. causing bond in substrate to distort lowering activation energy

Question 4

describe how models of enzyme action have changed over time

Answer 4

initally lock and key model
- active site a fixed shape complementary to one substrate
now iduced fit

Question 5

explain the specifity of enzymes

Answer 5

specific tertiary strucure determines shape of active site
- dependant on sequence of amino acids
active site only complementary to a specific substrate
only this substrate can bind to active site forming enzyme-substrate complex

Question 6

describe and explain the effect of enzyme conc. on the rate of enzyme-controlled reactions

Answer 6

as enxyme conc. increases rate increases
- enzyme conc. = limiting factor
- more enzymes so more available active sites
- so more E-S complexes form

at certain point rate stops increasing
- substrate conc. = limiting factor

Question 7

describe and explain the effect of substrate conc. on the rate of enzyme controlled reactions

Answer 7

as substrate conc. increases rate increases
- substrate conc. = limiting factor
- more E-S complexes

at certain point rate stops increasing
- enzyme conc. = limiting factor
- all active sites saturated

Question 8

describe and explain the effect of temperature on the rate of enzyme controlled reactions

Answer 8

as temp increases to optimum rate increases
- more kinetic energy
- so more E-S complexes form

as temp increases above optimum rate decreases
- enzymes denature-tertiary structure and active site change shape
- hydrogen/ionic bonds break
- so no longer complementary
- fewer E-S complexes

Question 9

describe and explain the effect of pH on the rate of enzymes controlled reactions

Answer 9

as pH increases/decreases abobe/below optimum rate decreases
- enzymes denature-tertiary structure and active site change shape
- hydrogen/ionic bonds break
- so no longer complementary
- fewer E-S complexes

Question 10

describe and explain the effext of conc. of competitive inhibitors on the rate of enzyme controlled reactions

Answer 10

as conc. of competitive inhibitor increases rate decreases
- similar shape to substrate
- competes for active sites
- so substrate cant bind
- fewer E-S complexes

increasing substrate conc. reduces effect of inhibitor

Question 11

describe and explain the effect of conc. of non competitive inhibitors on the rate of enzyme controlled reactions

Answer 11

as conc. of non competitive inhibitor increases rate decreases
- binds to site other than the active site
changes enzyme tertiary structure
- so active site no longer complementary to substrate
- fewer E-S complexes

increasing sunstrate conc. has no effect on rate as change to active site is permanent