Enzymes And Rates Of Reaction Flashcards

1
Q

Why are enzymes studied

A
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2
Q

What do enzymes do

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3
Q

What are the characteristics of enzymes

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4
Q

What is the definition of an enzyme, active site and substrate

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5
Q

What are the characteristics of the active site of an enzyme

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6
Q

Name the 3 models used to describe how enzymes bind to substrates

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7
Q

What is the lock and key model

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8
Q

Describe the induced fit model

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9
Q

What does hexokinase do

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10
Q

How are active sites of enzymes specific to their substrates

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11
Q

What is geometric specificity

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12
Q

Give an example of a permissive enzyme

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13
Q

What is stereospecificty

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14
Q

How do you determine whether an enantiomer is an R or S enantiomer

A

Find chiral centre first

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15
Q

What is YADH

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16
Q

How do you determine the priority of hydrogens in a prochiral molecule

A

React molecule with NAD

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17
Q

How are enzymes classified

A
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18
Q

What are the six classes of enzymes and the numbers they are assigned

A

Oxidoreductases= 1
Transferases= 2
Hydrolases = 3
Lyases = 4
Isomerases = 5
Ligases = 6

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19
Q

What do oxidoreductases do

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20
Q

What do transferases do

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21
Q

What do hydrolases do

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22
Q

What do lyases do

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23
Q

What do isomerases do

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24
Q

What do ligases do

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25
Q

What are cofactors

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26
Q

What are prosthetic groups

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27
Q

What are cosubstrates

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28
Q

What is a holoenzyme

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29
Q

What is an apoenzyme

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30
Q

What is a coenzyme

A

An organic molecule that helps facilitate the action of enzymes

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31
Q

Why are vitamins needed

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32
Q

Name some examples of cofactors

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33
Q

How are enzymes linked to health

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34
Q

What are some examples of enzyme markers and what do they mark

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35
Q

What does thermodynamics tell us

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36
Q

How may a reaction progress steps wise

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37
Q

What is the general rate equation

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38
Q

What is the overall order of a reaction

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39
Q

What is meant by the order of a reaction

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40
Q

What is a first order reaction

A

Rate is directly proportional to concentration (as conc increases, rate increases)
Half life unaffected by conc

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41
Q

What is a second order reaction

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42
Q

What is a third order reaction

A

Or two molecules of one reactant and one of another or it involves three molecules of a single reactant

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43
Q

What is the rate equator for a first order reaction

A

Rate (or v)= k[A]

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44
Q

What is the rate equation for a reaction that is reversible

A

(Only reversible reactions have an equilibrium position)

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45
Q

What are the possible rate equations for a second order reaction

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46
Q

What is instantaneous rate

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47
Q

What is the integrated law for first order reactions using logarithms

A

[A]0 is initial conc of reactant
k is the rate constant

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48
Q

What is the integrated law for first order reactions using exponential

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49
Q

What is the graph shape for an ln[A]-time graph for a first order reaction and what does the gradient mean

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50
Q

What is the shape of a conc-time graph for a first order reaction

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51
Q

What is the shape of a rate-conc graph for a first order reaction

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52
Q

What is the shape of a conc-time graph for a second order reaction

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53
Q

What is the shape of a rate-conc graph for a second order reaction

A
54
Q

What is the shape of a conc-time graph for a zero order reaction

A
55
Q

What is the shape of a rate-conc graph for a zero order reaction

A
56
Q

What is meant by half life

A
57
Q

How do you calculate the half life for a first order reaction

A
58
Q

What is the integrated rate law fora second order reaction

A
59
Q

What are integrated rate laws used for

A

integrated rate laws express the reaction rate as a function of the initial concentration and a measured (actual) concentration of one or more reactants after a specific amount of time (t) has passed; they are used to determine the rate constant and the reaction order from experimental data.

60
Q

What is the shape of a 1/[A]-time graph for a second order reaction

A
61
Q

How do you calculate the half life of a second order reaction

A
62
Q

What is the rate determining step

A

Slowest step in a multistep reaction

63
Q

How can rate laws be determined experimentally

A
64
Q

What is collision theory

A
65
Q

What is an ineffective collision

A

If molecules collide in the wrong orientation and/or have insufficient kinetic energy

66
Q

Draw and explain an potential energy profile diagram

A
67
Q

What happens if collision energy >Ea

What happens if collision energy <Ea

A
68
Q

What is the potential energy profile for an exothermic reaction

A

Ea for forward exothermic reaction is < Ea for backward reaction

69
Q

What is the potential energy profile for an endothermic reaction

A

Ea for forward exothermic reaction is > Ea for backward reaction

70
Q

Draw the Maxwell - Boltzmann distribution curve and explain it

A

At a temperature T1, a certain fraction of the reactant
molecules have sufficient K.E., i.e. K.E. > Ea.
At a higher temperature T2, a greater fraction of the
molecules possess the necessary activation energy, and the reaction proceeds at a faster rate.

71
Q

Write the Arrhenius equation

A

A and Ea= Arrhenius parameters
Ea units kj mol-1
A =same units as k
k= rate constant
R =8.314
T =temp in Kelvin

72
Q

What can be derived from an Arrhenius plot

A
73
Q

What does it mean if an Arrhenius plot has a steep or shallow slope

A
74
Q

How do you find the activation energy for a reaction occurring at 2 different temps

A
75
Q

How can you increase the rate of reaction

A
76
Q

What is a transition state

A

It is a transient configuration of atoms where the bonds in the reactants are partially broken, and new bonds in the products are partially formed. This state is often denoted by the double dagger symbol

77
Q

What is meant by a zero order reaction

A

Conc has no effect on rate
Half life dec as conc dec

78
Q

What are the characteristics of the active site of an enzyme

A
79
Q

How do enzymes increase the rate of reaction

A
80
Q

What does metastable mean

A

stable provided it is subjected to no more than small disturbances

81
Q

Draw a potential energy profile including the transition state

A
82
Q

Write the general equation for a reaction including is transition state

A
83
Q

What is meant by this symbol

A

Activation energy

84
Q

How can the concentration of the transition state be used to find the rate of reaction of a catalysed reaction

A
85
Q

How can the concentration of the transition state be used to find the equilibrium constant of a catalysed reaction

A
86
Q

How can the rate constant of catalysed reaction be found

A
87
Q

Recall the eyring equation and what it tells us

A
88
Q

What is the relationship between free energy change and the rate constant

A
89
Q

What is the linear form of the eyring equation and what does it look like graphically
What can be found from the slope and y intercept of the graph

A
90
Q

How do enzymes increase the rate of reaction

A
91
Q

What is meant by this symbol and how is it calculated

A

Change in Ea

92
Q

Explain the pathway of catalysis using this diagram

A
93
Q

How do enzymes decrease Ea

A
94
Q

Draw the potential energy diagram for when there is no enzyme

A
95
Q

Draw the potential energy diagram for when the enzyme is complimentary to the substrate

A
96
Q

Draw the potential energy diagram for when the enzyme is complimentary to the transition state

A
97
Q

What rate law does enzyme bound substrates follow

A

First order

98
Q

Why is there a decrease in entropy when the substrate binds to an enzyme

A
99
Q

Draw and label a reaction profile for a reaction with multiple steps

A
100
Q

What is tyrosyl tRNA synthase

A
101
Q

What does this symbol tell us

A
102
Q

What does this symbol tell us

A
103
Q

What are transition state analogues

A

Can synthesise molecules that have a similar structure to the transition state that are stable
Since transition state molecules can’t be isolated but can be predicted

104
Q

What can transition state analogs be used for

A
105
Q

What can catalytic antibodies be used todo

A
106
Q

What are abzymes and what are they used for

A
107
Q

What is the Hammond postulate

A

( so their interconversion would only require some molecular reorganisation)
It can be used to predict the structure of the transition state

108
Q

How does the Hammond postulate link to endo and exothermic reactions

A
109
Q

What is desolvation

A
110
Q

How does distortion occur to substrates when they bind to enzymes

A

This achieves a transition state with less energy (more stable)

111
Q

How do enzymes increase the chance of a reaction occurring

A
112
Q

What are the different types of enzyme assays

A
113
Q

What are enzyme assays used for

A
114
Q

What factors need to be taken into account when developing an assay

A
115
Q

What are the factors that can affect an assay

A
116
Q

What do the different curves on this graph mean

A
117
Q

What are the units used to measure activity in an assay

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118
Q

What should be considered during assay development

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119
Q

What are continuous assays

A
120
Q

What methods can be used to measure change in [s] in a continuous assay

A
121
Q

When is using a spectrophotometer appropriate for an assay

A
122
Q

What are the limitations of using a spectrophotometer in an enzyme assay

A

Limitations of spectrophotometry include a relatively low sensitivity and selectivity. It may thus be difficult to detect very low concentrations of an analyte or distinguish the analyte from other substances that absorb light on the same wavelength.

123
Q

What are coupled reaction assays

A
124
Q

What considerations should be made when using a coupled reaction

A
125
Q

What is a fluorimetric assay

A
126
Q

What are chemiluminescent assays

A
127
Q

What are discontinuous /fixed time assays

A
128
Q

What methods can be used to measure fixed assay data

A
129
Q

What may interfere with your assay

A
130
Q

Have can you further optimise your assay

A
131
Q

What is the difference between continuous and discontinuous assays

A

Enzyme assays can be split into two groups according to their sampling method: continuous assays, where the assay gives a continuous reading of activity, and discontinuous assays, where samples are taken, the reaction stopped and then the concentration of substrates/products determined.