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enzymes Flashcards

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AP® Biology flashcards
1
Q

what is metabolism?

A

the combination of anabolic and catabolic reactions that are catalysed by enzymes

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2
Q

what is a metabolic pathway?

A

a series of enzyme controlled reactions.
product of one is the reactant in the next

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3
Q

what are anabolic reactions?

A

build up molecules
e.g. protein synthesis

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4
Q

what are catabolic reactions?

A

break down molecules
e.g. digestion

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5
Q

definition of enzyme

A

a biological catalyst, globular protein, that alters the rate of a chemical reaction without being used up.
remains unchanged

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6
Q

why are enzymes called a biological catalyst?

A

they are made up of living cells
they lower activation energy

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7
Q

properties of enzymes

A

they:
speed up reactions
aren’t catalysed
aren’t used up
have a high turn-over number
are soluble

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8
Q

structure of enzymes

A

protein tertiary structure
active site with specific 3D shape

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9
Q

where are the sites of enzyme action

A

extracellular
intracellular (in solution or membrane bound)

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10
Q

extracellular enzyme action

A

outside cells
enzymes secreted by exocytosis
e.g. amylase produced in salivary glands

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11
Q

intracellular enzyme action in solution

A

inside cells
e.g. enzymes in glycolysis, cytoplasm respiration

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12
Q

intracellular enzyme action membrane bound

A

attached to membranes
e.g. mitochondria cristae, chloroplast grana

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13
Q

role of the active site

A

enzymes act on its substrate, making temporary bonds at the active site
form enzyme substrate complexes

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14
Q

what is an enzyme substrate complex

A

temporary molecule formed when the substrate binds to the enzyme

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15
Q

what is the lock and key model

A

substrate and active site have a complementary shape
only substrates that exactly fit the enzyme can be catalysed
enzymes are specific to 1 substrate

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16
Q

enzyme specificity

A

enzymes are specific to 1 substrate

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17
Q

what is the induced fit model

A

substrate binds to enzymes active site
shape of active site changes slightly
esc formed
product released

18
Q

lysozyme and the induced fit model

A
  • antibacterial enzyme in mucus, saliva, tears
  • folds around sugars in cell wall of bacteria
    disrupts structure
    breaks bonds
    bacterial cell wall absorbs water = bursts
19
Q

what is activation energy

A

the minimum energy put into a chemical system for a reaction to occur
molecules need enough KE to collide and react

20
Q

what is catalysis?

A

the lowering of activation energy

21
Q

what is the collision theory?

A

for a reaction to occur, particles involved must collide with enough energy so bonds are broken
higher temp = higher KE = more successful collisions = more ESCs formed

22
Q

how do different factors change enzyme action?

A

environmental conditions alter the 3D structure of enzymes
bonds in tertiary structure break = changes shape of active site = reduces ability to form ESCs = lowers reaction rate

23
Q

what is denaturation?

A

the permanent change of an enzymes structure
due to high temps or extreme pHs

24
Q

affect of low temperature on enzymes

A

particles have low KE
few successful collisions
less ESCs formed per unit time
fewer product formed

25
Q

affect of extremally high temperature on enzymes

A

KE increases
vibrations in enzyme molecules weaken bonds holding the 3D tertiary structure of active site together
active site loses shape
substrate no longer complementary
no more ESCs
enzyme denatured

26
Q

affect of extreme pH on enzymes

A

small changes from optimum = reversible changes in enzymes = reduces efficiency
large change from optimum = disrupts ionic / hydrogen bonds in enzyme = permanent changes to shape of active site = prevents ESC formation = enzyme denatures

27
Q

affect of enzyme concentration on enzymes

A

excess substrate, increase in enzyme conc = increased reaction rate (plenty of active sites)
not in excess = substrate limiting = no effect of adding more enzymes

28
Q

affect of substrate concentration on enzymes

A

increased substrate conc = increase collisions = higher reaction rate
eventually further substrate increase = no effect, enzymes all have full active sites (enzyme conc limiting)

29
Q

what are pH buffers?

A

counteract changes in pH
neutralise acid or alkaline

30
Q

what is a cofactor

A

a non-protein substrate that binds to an enzyme allowing a reaction to occur

31
Q

what is an inhibitor?

A

a molecule/ion that binds to an enzyme, reducing the rate of reaction by interfering with the shape of the active site
reversible or irreversible

32
Q

what is a competitive inhibitor?

A

complementary in shape to active site of enzyme
prevents ESC formation by blocking the active site
don’t bind permanently
- increases substrate conc reduces the effect

33
Q

what is an non-competitive inhibitor?

A

bind to enzyme away from active site, at allosteric site.
alter shape of active site
no ESCs form
always produces a lower rate of reaction

34
Q

what are calibration curves?

A

used to predict the concentration of unknown solutions based on comparing concentrations of known solutions

35
Q

what are immobilised enzymes?

A

enzymes fixed, bound or trapped in an inert matrix
e.g. cellulose microfibrils, sodium alginate beads

36
Q

advantages of immobilised enzymes

A
  • increased stability = dentatutre at higher temps, used over wider range of pH
  • products uncontaminated with enzyme
  • enzymes easily added and removed = control over reaction
  • enzymes easily recovered for reuse
37
Q

uses of immobilised enzymes

A
  • lactose free milk
  • high fructose corn syrup
  • biosensors
38
Q

how are immobilised enzymes used in making lactose free milk?

A

milk passed down column containing immobilised enzymes
lactose binds to active site on lactase

39
Q

what are biosensors?

A

convert chemical into electrical energy
used in blood glucose detection

40
Q

why is it more efficient to use enzyme immobilised onto a membrane than in beads?

A

it takes longer for substrate to diffuse into the beads to reach the centre where the active site is

41
Q

why does reducing flow rate increase the volume of product in immobilised enzymes?

A
  • increases contact time between enzyme and substrate
  • more time for enzyme to function
  • more successful collisions
  • more ESCs form

biology eduquas (11 decks)

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