2.4 Enzymes Flashcards

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1
Q

What are enzymes

A

-proteins made inside cells in the ribosomes
-biological catalysts

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2
Q

What is the tertiary structure

A

the final shape of an enzyme which is determined by the sequence of amino acids

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3
Q

what are catalysts

A

substances which speed up biochemical reactions

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4
Q

what can enzymes be affected by

A

-Ph
-temperature

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5
Q

what is the turn over rate

A

how fast an enzyme works

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6
Q

what can the active site and shape of substrate be described as

A

complementary

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7
Q

identify some examples of enzymes

A

-catalse
-amylase
-pepsin
-lipase
-maltase
-trypsin

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8
Q

where is catalase found and what does it do

A

in most living organisms that are exposed to oxygen
breaks down harmful hydrogen peroxide

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9
Q

what sort of enzyme is catalyse

A

intracellular

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10
Q

where is catalase found in eukaryotes

A

peroxisomes

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11
Q

what sort of reactions do enzymes catalyse

A

metabolic

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12
Q

identify some extracellular enzymes

A

amylase
trypsin

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13
Q

why may an enzyme not function

A

doesn’t have its amino acids in the correct order

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14
Q

why are enzymes specific

A

they all have differently shaped action sites

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15
Q

define extracellular

A

excreted onto substance

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16
Q

define intracellular

A

substrate acted upon inside cells

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17
Q

what is the enzyme product complex

A

enzyme molecule with product molecules in its action site

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18
Q

what is the enzyme-substrate complex

A

enzyme molecule with substrate molecules in its active site

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19
Q

what is the product of the enzyme substrate complex

A

smaller product molecules

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20
Q

what is the product of the enzyme product complex

A

one larger product molecule

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21
Q

what is the lock and key hypothesis

A

that the substrate fits perfectly into the enzyme

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22
Q

what is the induced fit hypothesis

A

the active site is still complementary to the substrate but its active site changes shape to mould around it

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23
Q

what does catabolic mean

A

breaks down molecules

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24
Q

what does anabolic mean

A

builds up molecules

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25
Q

what shape are enzymes

A

globular

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26
Q

what is hydrogen peroxide

A

a bi product of many metabolic reactions

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27
Q

what is the equation for the break down of hydrogen peroxide

A

hydrogen peroxide —-> water + oxygen +energy
catalase

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28
Q

what is a limiting factor

A

factor which can alter the rate of a reaction if all other factors are kept constant

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29
Q

what happens if enzyme concentration increases

A

-more active sites are available
-more successful collisions

30
Q

what happens if an enzymes temperature increases

A

bonds break, tertiary structure unravels, the active site shape is lost and the enzyme denature

31
Q

how does denaturation by heating happen

A

heating increases kinetic energy =more collisions
molecules vibrate more so bonds break
substrate is no longer complementary to active site

32
Q

what are the properties of enzymes

A

-globular
-soluble in water
-3d tertiary structure
-catalysts
-specific

33
Q

what is an inhibitor

A

a substance that reduces or stops a reaction

34
Q

what is competitive inhibition

A

substances similar to the substrate which can occupy active sites without triggering reactions inhibiting enzyme activity

35
Q

what is non-competitive inhibition

A

inhibitors that can block or change the shape of the active site of an enzyme by binding to the allosteric site

36
Q

what is substrate inhibition

A

excess substrate which can compete for the active site, slowing the reaction speed

37
Q

what is end product inhibition

A

after the catalysed reaction has reached completion, product molecules stay slightly bound to the enzyme. The enzyme cannot form more of the product than the cell needs

38
Q

how are metabolic sequences controlled

A

the product of one enzyme becomes the substrate for the next enzyme catalysed reaction in the metabolic pathway

39
Q

what happens when the product of the last enzyme catalysed reaction attaches to a part of the first enzyme in the pathway

A

this binding changes the shape of enzyme 1’s active site, preventing the pathway from running

40
Q

what is a buffer

A

something that resists changes in PH

41
Q

what will you use buffer solutions for in lab investigations

A

to maintain desired PH for investigating enzyme action at different PH values or to keep the PH constant whilst investigating another factor

42
Q

how do changes in PH affect bonds within molecules

A

excess hydrogen ions interfere with hydrogen bonds and ionic forces so the active site of the enzyme will change

43
Q

how does increasing the concentration of hydrogen ions affect the active site

A

protons cluster around negatively charged groups
this interferes with the binding

44
Q

what happens if there is a small change in PH

A

active site is disrupted
rate of reaction is slow

45
Q

what happens if the optimum PH is restored

A

hydrogen bonds reform and the active site shape is restored

46
Q

what happens at extremes of PH

A

enzymes denatures

47
Q

what is the optimum Ph of intracellular enzymes

A

close to 7

48
Q

what is the optimum PH of extracellular enzymes

A

they differ

49
Q

what is an example of intracellular enzymes + PH

A

during digestion, amylase that digests starch to maltose works best at a PH of 6.8

50
Q

what is an example of extracellular enzymes + PH

A

As food passes in your stomach, hydrochloric acid is secreted giving a low PH. Pepsin works best at values between 1 and 2.

51
Q

what are coenzymes

A

organic molecules that bind to enzymes to help them function

52
Q

what are the 3 types of cofactors

A

-prosthetic groups
-ions
-coenzymes

53
Q

what is an example of a coenzyme

A

-NADP
-Coenzyme A

54
Q

are coenzymes organic

A

yes, organic vitamins

55
Q

what is a coenzymes method of action

A

binds permanently/not permanently dependant if enzyme contains carbon

56
Q

what is an example of an inorganic ion factor

A

chloride ion

57
Q

what is the method of action of an inorganic ion factor

A

changes the charge distribution on the surface of the substrate molecule

58
Q

what is an example of a prosthetic group

A

zinc

59
Q

are prosthetic groups organic

A

no

60
Q

what is the method of action of prosthetic groups

A

binds permanently to the active site

61
Q

what is carbonic anhydrase

A

an enzyme that catalyses the reaction between CO2 and H2O to form carbonic acid in red blood cells which only functions when a prosthetic group is permanently attached

62
Q

what are examples of poison inhibitors

A

-cyanide
-snake venom

63
Q

what does cyanide do

A

inhibits respiratory enzymes (cytochrome oxidase) and changes the shape of active site which stops respiration

64
Q

what does cyanide affect

A

reactions requiring ATP are no longer supplied so there is no energy which causes cell failure

65
Q

what does snake venom do

A

inhibits enzyme (acetylcholinesterase) used to degrade the neurotransmitter acetylcholine

66
Q

what is the effect of snake venom

A

stops nerve impulses from being transmitted and stops muscle contraction- leads to flaccid paralysis

67
Q

what are examples of medicinal inhibitors

A

-aspirin
-protease

68
Q

what does aspirin do

A

contains salicylic acid and binds to enzymes which catalase the formation of prostaglandins

69
Q

what is the effect of aspirin

A

prevents the formation of prostaglandins which make nerves more sensitive to pain and swelling

70
Q

what does protease do

A

stops protease cutting viral RNA into smaller pieces. The virus can’t inject its RNA into a host cell to replicate