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Enzymes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what are reactions catalysed by

A

enzymes

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2
Q

what are enzymees

A

biological catalysts

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3
Q

what type of protein are enzyme

A

globular

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4
Q

what do enzymes do

A

interact with a substrate molecules causing them to react at much faster rates without the need for harsh environment conditions

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5
Q

what are chemical reactions required growth called

A

anabolicw

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6
Q

where is energy released from

A

large organic molecules (glucose)o

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7
Q

how is energy released from large organic molecules

A

in metabolic pathways consisting of catabolic reactions (breaking down reactions)

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8
Q

how are these large organic molecules obtained

A

from the digestion of food

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9
Q

what is the specificity of the enzyme

A

each enzyme catalyses one biochemical reaction

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10
Q

what is activation energy

A

energy needs to be supplied for most reactions to start

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11
Q

what can enzymes help with

A

for molecules collide successfully and reduce the activation energy required

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12
Q

describe the lock and key hypothesis

A

only a specific substrate can fit into an enzyme’s active site
when the substrate is bound to the active site, an enzyme-substrate complex is formed
- the substrate then react and the product is formed in an enzyme-product complex
- the product is then release, leaving the enzyme unchanged and able to take part in subsequent reactions

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13
Q

what puts strain on the bond in the substrate

A

the substrate is held in such a way by the enzyme that the right atom-groups are close enough to react, the R-groups within the acitve site of the enzyme will also interact with the substrate forming temporary bonds

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14
Q

what is an induced-fit hypothesis

A

the active site of the enzyme actually changes shape slightly as the substrate enters

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15
Q

describe the initial intereaction between the enzyme and substrate in induced-fit hypothesis

A

it is relatively weak but these weak interactions rapidly induce changes in the enzymes tertiary sturcture that strengthen binding, putting strain on the substrate molecule

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16
Q

what are intracellular enzymes

A

enzymes that act within cells

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17
Q

give an example of intracellular enzymes

A

the synthesis of polymers from monomers, making polysaccharides from glucose, requires enzymes
catalase helps break down hydorgen peroxide

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18
Q

what supplies raw materials (substrates)

A

nutrients

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19
Q

what form are nutrients in

A

polymers such as proteins and polysaccharides

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20
Q

why do nutrients need to be broken down intosmaller components

A

they are too large to enter through the cell-surface membrane

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21
Q

how are these nutrients broken down

A

by enzymes through the process of digestion (extracellular enzymes)

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22
Q

what are extracellular enzymes

A

they work outside the cell that made them

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23
Q

how do single-celled organisms use extracellular enzymes

A

eg. bacteria and yeast, release enzymes into their immediate environment, extracellular enzymes break down the larger molecules (proteins) produce smaller molecules (amino acids and glucose) are absorbed by the cell

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24
Q

how do multicellular organisms use extracellular enzymes

A

the large molecules still have to be digested so smaller molecules can be absorbed into the bloodstream, from there, they are transported around the body to be used as substrates in cellular reactions

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25
Q

example of extracellular enzymes in multicellular organisms

A

involved in digestion in humans are amylase and trypsin

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26
Q

describe the first step of the digestion of starch

A

Starch polymers are partially broken into maltose, which is a disaccharide. The enzyme involved in this stage is called amylase. amylase is produced by the salivary glands and the pancreas, it is released in saliva into the mouth, and in pancreatic juice into the small inestine.

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27
Q

describe the second step of the digestion of starch

A

maltose is then broken down into glucose, which is a monosaccharide. the enzyme involved in this stage is called maltase, maltase is present in the small intestine

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28
Q

describe digestion of proteins

A

trypsin is a protease (type of enzyme that catalyses the digestion of proteins into smaller peptides, whcih can then be broken down further into amino acids by proteases.) Trypsin is produced in the pancrease and released with the pancreactic juice into the small intestine, the amino acids produced are absorbed by the cells lining the digestive system and then absorbed into the bloodstream

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29
Q

what biological molecule forms an enzyme

A

protein

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30
Q

what are the monomers that form proteins

A

amino acids

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31
Q

describe how the structure of proteins determines enzyme activity

A

specific 3D shape, tertiary structure, active site binds to substrate and catalyses reaction

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32
Q

explain how catabolism and anabolism are related to metabolism

A

catabolism is breaking down of molecules, anabolism is building of molecules, reactions involve breaking down and building of molecules

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33
Q

explain lock and key, and induced-fit

A

both models substrate interact with R-groups in active site binds leading to bond strain in substrate molecule, lock and key substrate is complementary to active site, induced-fit active site is flexible, it changes shape as substrate binds, closer fit between active site and substrate

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34
Q

are enzymes more likely to come into contact with the substrate at a high or low temperature

A

high

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35
Q

what needs to happen for an enzyme to catatlyse a reaction

A

they must come into contact with the substrate and the enzyme must be the right shape

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36
Q

what can an enzymes structure be affected by

A

temperature and pH

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37
Q

describe temperature of being an effect of enzymes

A

increasing temperature increases kinetic energy in particles
so the particles more faster and collide more frequently so an increase in rate of reaction

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38
Q

what is the temperature coefficient Q10

A

a measure of how much the rate of reaction increases with a 10oC rise in temperature
in an enzyme controlled reaction this is taken as 2 so it doubles

39
Q

describe denaturation from temperature

A

at high temps the bonds holding the protein together vibrate more
as the temp increases the vibrations increase until the bond strain and then break
this results in a change in the precise tertiary structure of the protein and the enzyme has been denatured

40
Q

what happens when an enzyme has been denatured

A

the active site changes shape and is no longer complementary to the substrate so the substrate no longer fits into the active site and the enzyme will no longer function as a catalyst

41
Q

what is the optimum temperature

A

the enzyme has the highest rate of activity and the temperatures can vary, many enzymes in the human body have an optimum temperature of 40oC

42
Q

what happens when an enzymes temperature increases over its optimum temperature

A

it decreases in rate of reaction rapidly

43
Q

what happens to an enzymes rate of reaction when it hasn’t reached optimum yet

A

it decreases in rate of reaction but not as rapid as it hasn’t denatured yet

44
Q

give examples of extremely cold environment

A

deep oceans, high alititudes and polar regions

45
Q

give properties of enzymes that are adapted to the cold

A

tend to have more flexible structures mainly at the active site
making them stable than enzymes that work at higher temperatures

46
Q

describe thermophiles

A

organisms adapted toliving in very hot environments
enzymes present in these organisms are more stable than other enzymes
this is because they will have an increased number of bonds, mainly hydrogen bonds

47
Q

what does a chnage in pH also mean

A

a chnage in hydrogen ion concentration, more hydrogen ions are present in low pH environments

48
Q

what is optimum pH

A

active site will only be in the right shape at a certain hydrogen ion concentration

49
Q

describe bonding in proteins

A

hydrogen and ionic bonds between amino acid R-groups hold proteins in their precise 3D shape
these bonds result from interactions between the polar and charged R-groups present on the amino acids forming the primary structure

50
Q

what is renaturation

A

if pH returns to optimum after denaturing the protein will resume its normal shape and catalyse reaction agin

51
Q

will enzyme renature if pH changes significantly

A

no

52
Q

when pH is low are R-groups able to interact with each other as much

A

no, it leads tobond breaking and shape of enzyme chnaging

53
Q

what enzyme is present in saliva

A

amylase (pH 7-8)

54
Q

what is function of amylase

A

turns starch into maltose

55
Q

what enzyme is present in the stomach

A

pepsin (pH 1-2)

56
Q

what is the function ofpepsin

A

turns proteins into polypeptides

57
Q

what enzymes are present in pancreatic juice

A

trypsin, lipase, amylase, maltase (pH 8)

58
Q

what is the function of trypsin

A

turns proteins into polypeptides

59
Q

what is the function of lipase

A

turns triglycerides into glycerol and fatty acids

60
Q

what is the function of maltase

A

turns maltose into glucose

61
Q

what does a high concentration of substarte lead to

A

a higher collision rate with the active sites of enzymes and the formaiton of enzyme-substrate complexes, rate of reaction increases

62
Q

what does a high cocnentration of enzyme lead to

A

increase number of available active sites in a particular area or volume

63
Q

what happens when the rate of reaction increases up to (Vmax) maximum

A

all of the active sites are occupied by susbtrate particles and no more enzyme-substrate complexes can be formed until products are released from active sites

64
Q

why is it important that cellular condiitons are kept within narrow limits

A

so that enzyme activity is not delayed, ensure it is at a rate fast enough to sustain living processes

65
Q

why cant reactions happen too fast

A

lead to the build up of excess products

66
Q

what can enzymes be activated by?

A

cofactors

67
Q

what can enzymes be inactivated by

A

inhibitors

68
Q

what are inhibitors

A

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

69
Q

what are the two types of inhibitors

A

competitive and non competitive

70
Q

how comeptitive inhibitors work

A

a molecule that has a similar shape to the substrate can fit into the active site, this blocks the substrate from entering the active site

71
Q

what happens when a substrate and inhibitor molecules present in a solution

A

will compete with each other to bind to the active sites of the enzymes catalysing the reaction, reducing the number of substrate molecules binding to active sites (slows rate of reaction)

72
Q

is a competitive inhibitor effect reversible

A

yes as it is only temporary (apart from aspirin)

73
Q

what is the effect on rate of reaction with competitive inhibitors

A

reduces rate of reaction for a given concentration of substrate, does not change Vmax

74
Q

whats an example of competitive inhibitor

A

statins - used in synthesis of chloesterol
aspirin - irreversible

75
Q

how does a non competitive inhibitor work

A

inhibitor binds to the enzyme at a location called allosteric site
this causes the tertiary structure of the enzyme to change (active site changes)

76
Q

how does a non competitve inhibitor effect rate of reaction

A

increasing concentration of enzyme or substrate will not overcome the effect of a non competitive inhibitor, increasing concentration of inhibitor decreases rate of reaction

77
Q

what is the end product inhibition

A

enzyme inhibition that occurs when the product acts an a inhibitor to the enzyme that produces it

78
Q

example of non competitive inhibitors

A

prton pump inhibitors used to treat long term indigestion, irreversibly block an enzyme system responsible for secreting hydrogen ions into the stomach

79
Q

what is end product inhibition an example of

A

non competitive inhibiotr

80
Q

describe respiration

A

a metabolic pathway resulting in production of ATP, glucose is broken down in a number of steps

81
Q

what is a cofactor

A

a non protein substance that bounds to enzymes in order for some of them to work

82
Q

what are inorganic factors

A
  • they work by helping the enzyme and substrate bind together
  • thye dont directly participate in the reaction so arent used up or changed in any way
  • eg. chloride ions are inorganic cofactors for the enzyme amylase
83
Q

what are organic cofactors (Coenzymes)

A
  • they participate in the reaction and are changed by it
  • they often act as carriers moving chemical groups between different enzymes
  • eg. vitamins
84
Q

what are prosthetic groups

A

when a cofactor is tightly bound to the enzyme

85
Q

give an example of a prosthetic group

A

zinc ions are prosthetic group for carbonic anhydrase and are a permanent part of the enzymes active site

86
Q

whats the name of when enzymes are produced in an inactive form

A

inactive precursor enzymes

87
Q

why does a cofactor need to be added to a precursor protien

A

they often need a change in tertiary structure mainly to the active site to be activated

88
Q

what is the precursor protein called before a cofactor is added

A

apoenzyme

89
Q

what is the precursor protein called after a cofactor is added

A

holoenzyme

90
Q

what is the word equation for the reaction controlled by catalase?

A

hydrogen peroxide -> water + oxygen

91
Q

why is it important to keep all the cylinders the same size in the practical effect of substrate concentration on rate of enzyme controlled reaction

A

the surface area must be controlled as the surface area affects the speed at which substance can reach the active site

92
Q

explain the shape of the graph from the effect of substrate concentration on the rate of an enzyme controlled reaction

A

as the concentration of the hydrogen peroxide increases, there is more substrate available to bind with the active site of catalase via complementary binding, increases each volumes

93
Q

state 2 limitations of the effect on substrate concentration

A

cannot control temperature and cannot control the concentration

94
Q

how to change these limitations

A

leave cylinders in a water bath at room temp
use solution of enzyme catalase of known volume and concentration

Biology (28 decks)

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