enzymes Flashcards

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1
Q

what is the role of enzymes

A

to speed up metabolic reactions in living organisms

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2
Q

why can enzyme be reused?

A

they remain unchanged

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3
Q

give 3 benefits of enzymes compared to chemical catalysts

A

they can be re-used
they work well in body conditions
they are specific for certain reaction

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4
Q

what is an anabolic reaction

A

breaking 1 substrate into 2 products

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5
Q

what is a catabolic reaction

A

2 substrates need to break to result in one product

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6
Q

describe how an anobolic reaction occurs

A

the enzyme holds 2 molecules close together at the active site and the bonds then join them together

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7
Q

describe how a catabolic reaction occurs

A

the active site holds the substrate in the correct position to put a strain on certain bonds, the bonds break gibing 2 products

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8
Q

what are intracellular enzymes

A

act inside a cell

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9
Q

what is the enzyme called which breaks down hydrogen peroxide

A

catalase

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10
Q

what is the equation for the break down of hydrogen peroxide

A

2H2O2–> 2H2O+O2

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11
Q

what is the turnover of the enzyme catalase

A

6 million per second

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12
Q

what is a metabolic pathway

A

a series of enzymes that result in the final product

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13
Q

what is an extracellular enzyme

A

enzymes that are secreted out of the cell

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14
Q

give an example of an extracellular enzyme

A

digestive enzyme

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15
Q

what does amylase break down

A

starch

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16
Q

what does pepsin break down

A

proteins

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17
Q

what does lipase break down

A

lipids

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18
Q

what is fungi made up of

A

hyphae threads

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19
Q

what are 2 models for enzyme action called

A

lock and key model
induced fit

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20
Q

describe the lock and key model

A

the substrate is a complimentary shape to the active site of the enzyme (rigid shape) and fits in perfectly, chemically compatiable

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21
Q

describe the induced fit model

A

enzyme and substrate don’t fit perfectly, as the substrate fits into the active site there is a slight change in the shape of the active site (moulds around), they had to be chemically compatiable with eachother

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22
Q

why do cells only need a very small concentration of each different enxyme

A

can be re-used again and again

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23
Q

what does the Q10 value mean

A

the rate of reaction doubles for every 10 degree temperature rise

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24
Q

what is the equation for the Q10 value

A

ROR (T+10 degree)/ ROR at T degree

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25
Q

how does the structure of enzymes that are in extreme environments adapt

A

lots of disulfide bonds so as the temperature rises it does not change shape or denature

26
Q

draw the graph of change in pH

A
27
Q

what changes if the pH changes

A

the balance of ions change

28
Q

what bond does a change in pH affect

A

ionic bonds

29
Q

what is the ion for acids

A

H+

30
Q

what is the ion for alkalines

A

OH-

31
Q

what pH do most enzymes work best at

A

7

32
Q

what is used to fix the pH of a solution

A

buffer solution

33
Q

describe what happens when the substrate concentration increases

A

the ROR increases to a certain point, any further addition of the substrate does not increase the ROR

34
Q

describe how an enzyme catalyses a reaction

A

enzyme + substrate
creates an ESC
forms an EPC
enzyme + product

35
Q

describe what happens when the enzyme concentration increases

A

with more enzymes present, more substrates will bind to an empty active site on an enzyme, once there are no more substrates left the ROR has not continue

36
Q

explain why an increase in temperature increases the rate of enzyme activity

A

the enzyme and substrate will have more kinetic energy and collide more, so there is more ESC meaning more product is released

37
Q

what is an enzyme inhibitor

A

molecules that prevent enzymes from carrying out their normal function of catalysis

38
Q

what is a competitive inhibitor

A

a molecule that fits in the active site blocking the substrate and stops the catalytic reaction

39
Q

give an example of a competitive inhibitor

A

statins to reduce blood cholesterol concentration

40
Q

what is a non-competitive inhibitor

A

binds to the enzyme other than the active site (allosteric site)

41
Q

does substrate concentration affect the inhibitor in competitive inhibitors

A

yes

the substrate added, teh greater chance it will out compete the inhibitor for the active site and the more ROR will increase

42
Q

will increasing the substrate concentration make any difference to the ROR in a non-competitive inhibitor

A

no as the enzyme has permantly changed shape

43
Q

give an example of a non-competitive inhibitor

A

PPI’s (block enzyme activity which releases stomach acid to stop stomach ulsers)

44
Q

give 2 characteristics of a non-competitive inhibitor

A

irreversible

highly toxic

45
Q

give an example of an inhibitor which can be a metabolic poison and explain it

A

cyanide

attach to the enzyme involved in cellular respiration and causes the organism to die

46
Q

what is an ‘end-product inhibition’

A

when a product of a reaction can inhibit one of the enzymes involved in its own production

47
Q

why are ‘end product inhibition’ useful (2 ways)

A

regulates the metabolic pathway (don’t make too much product)

avoids wasting cell resources

48
Q

what are enzymes called when they are made in inactive forms

A

pre-cursors

49
Q

what is the reason for pre-cursors

A

to prevent damage of our cells

50
Q

what needs to happen for
pre-cursors to be activated

A

they need to undergo a change in shape of their active site with the help of co-enzymes and co-factors

51
Q

what helps change the change shape of the pre-cursors active site

A

adding a co-factor or co-enzyme

52
Q

what is a apoenzyme

A

a pre-cursor (inactive)

53
Q

what is a holoenzyme

A

an active pre-cursor

54
Q

give 2 characteristics of a co-factor

A

inorganic

not used up in a reaction

55
Q

give an example of a co-factor

A

chloride ions needed to activate salivary amylase which digests starch

56
Q

what are co-enzyme and co-factors

A

increase enzyme activity

57
Q

give 2 characteristics of co-enzymes

A

organic

altered by the reaction

58
Q

give an example of a co-enzyme

A

vitamins

59
Q

what is a prosthetic group

A

they are co-factors or co-enzymes that are tightly attached to an enzyme and may be permanently attached

60
Q

What do co-factors do to promote enzyme activity

A

Helping the enzyme and substrate join

61
Q

How do co-enzymes increase enzyme activity

A

They act as carriers moving chemical groups between different enzymes in metabolic pathways