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AS biology > 2.4 enzymes > Flashcards

2.4 enzymes Flashcards

1
Q

enzyme type of protein

A

globular

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2
Q

intracellular enzyme example

A

catalase
hydrogen peroxide -> hydrogen + water

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3
Q

extracellular enzyme example

A

amylase (starch-> maltose)
trypsin (protein -> amino acids)

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4
Q

active site

A
  • part of enzyme that the substrate binds to
  • COMPLEMENTARY and SPECIFIC shape
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5
Q

lock and key model

A
  • enzyme = lock, substrate -= key
  • specific shape (enzyme only catalyses ONE type of reaction)
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6
Q

how do enzymes catalyse reaction

A

alternative pathway with a lower activation energy

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7
Q

induced fit hyporthesis

A
  • AS of enzyme not perfectly completmentary
  • substrate moves into active site, interacts with active site, interferes with bonds and changes the shape of active site so its a perfect fit
  • affects bonds in substrate (easier to make or break)
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8
Q

4 steps of enzyme reaction

A
  1. enzyme and substrate (separate)
  2. enzyme substrate complex
  3. enzyme product complex
  4. enzyme and product (separate)
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9
Q

pH on enzyme

A
  • denatures at extremes
  • optimum differs for every enzyme
  • high conc of H+ ions
  • disrupt interactions between r groups (ionic bonds/H bonds)
  • change tertiary structure
  • substrate no longer can bind to active site
  • enzymedenatured
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10
Q

denaturing

A
  • tetriary structure altered
  • shape of active site changed
  • AS no longer complementary to subtrate
  • S cannot bind to form ESC
  • rate slows
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11
Q

typical optimum temperature in animals

A

37 degrees

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12
Q

effect of temp on enzymes

A
  • low temp enzymes are inactive, KE too low, infrequent collisions so few ESC formed
  • as temp increases, KE increases, move more quickly, more ES collisions so more ESC formed
  • temp too high, R group interactions in tertiary structure broken, shape changes, denatured
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13
Q

enzyme and substrate conc

A
  • as conc increases, rate increases up until v max
  • more frequent successful collisions between ACTIVE SITE and substrate
  • more ESC’s formed
  • plateau at v max (max rate)
  • active site saturation
  • substrate conc no longer limiting reagent- enzyme concentration is limiting
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14
Q

PRACTICAL CONSIDERATIONS (6)

A
  • vol and conc of enzyme
  • vol and conc of substrate
  • temperature control (thermostatic water bath)
  • pH control (buffer solution)
  • repeat and mean (reliability)
  • range bars
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15
Q

coenzymes

A
  • organic
  • take part in reaction and are changed
  • then recycled for other reactions- carry chemicals between enzymes
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16
Q

cofactors

A

non protein substance required by an enzyme in order to function

17
Q

prosthetic group

A
  • PERMANENT cofactor
  • contributes to final 3d shape
    eg Zn2+ in carbonic anhydrase
18
Q

coenzyme example

A

vitamins

19
Q

prosthetic group example

A

zinc in carbonic anhydrase

20
Q

inroganic ion cofactor + example

A
  • combine w enzyme or sustrate to allow ESC to form more easily
  • amylase and cl- ions
21
Q

competitive inhibitors explain

A
  • shape similar to substrate, complementary to active site
  • bind to active site, TEMPORARILY preventing substrate from entering
  • fewer active sites available for substrate
  • eventaully, substrate out competes inhibitor so rate reaches normal as more ESC formed
22
Q

non-competitivie inhibitors

A
  • fit into allosteric site
  • cause a confrimational change in the shape of the enzyme
  • affects active site, no longer complementary so substrate cant bind
22
Q

non-reversible inhibitors

A

bind permanently to enzyme

22
Q

product inhibition

A
  • product inhibits the enzyme
  • prevents too much product from being made
23
Q

reversible inhibitors

A

occupy ennzyme briefly

24
Q

Q10

A
  • for every 10 degree increase, how much rate is affected
  • CALCULATE: rate at t+10/rate at t
25
Q

effects of altering low temp vs high temp

A

low = REVERSIBLE
high = IRREVERSIBLE

26
Q

experiment for cofactor action

A
  • reaction without cofactor
  • with 3 diff concs of cofactor
  • control [enzyme], [substrate], optimum temp and pH
  • repeat and mean
27
Q

why do scientist accept induced fit over lock and key

A

more evidence to support

28
Q

evidence from graph of competitive

A
  • at high substrate conc
  • rate approaches rate WITHOUT inhibitor, as increased substrate conc overcomes inhibition
29
Q

how can you tell its a competitive inhibitor(visually)

A
  1. substrate and inhibitor similar shape
  2. specific shape complementary to active site, able to bind
  3. reference the same bond if shown

AS biology (14 decks)

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