Enzymes Flashcards
(166 cards)
1
Q
What is metabolism?
A
All the chemical reactions happening in an organism’s body.
Metabolism includes both anabolic and catabolic reactions.
2
Q
Define metabolic pathway.
A
A sequence of enzymes-controlled reactions, where the product of one reaction becomes the reactant of the next.
This pathway is crucial for the regulation and flow of biochemical processes.
3
Q
What are anabolic reactions?
A
Build up molecules.
These reactions require energy input, typically in the form of ATP.
4
Q
What are catabolic reactions?
A
Break down molecules.
These reactions release energy by breaking down complex molecules into simpler ones.
5
Q
What is an enzyme?
A
Globular proteins that are biological catalysts.
Enzymes facilitate biochemical reactions without being consumed in the process.
6
Q
What is a catalyst?
A
A chemical that speeds up the rate of chemical reactions without undergoing permanent changes themselves, or being used up.
Catalysts lower the activation energy needed for reactions.
7
Q
Define turnover number.
A
The number of reactions a second that enzymes/catalysts can catalyse.
This metric indicates the efficiency of an enzyme.
8
Q
What determines the shape and function of an enzyme’s active site?
A
The tertiary structure of the enzyme.
The active site is crucial for substrate binding and specificity.
9
Q
What is the active site?
A
The specific 3D shape site on the enzyme molecule to which the substrate binds by weak chemical bonds.
The shape of the active site is complementary to the substrate.
10
Q
Fill in the blank: Enzymes are proteins with a _______ structure.
A
tertiary
This structure is essential for their catalytic activity.
11
Q
True or False: Enzymes are consumed during the reactions they catalyze.
A
False
Enzymes can be reused multiple times in different reactions.
12
Q
What type of proteins are enzymes?
A
Globular proteins
13
Q
What are enzymes comprised of?
A
One or more polypeptide chains of amino acids linked by peptide bonds
14
Q
What forms the primary structure of an enzyme?
A
The sequence of amino acids
15
Q
What is the secondary structure of enzymes formed by?
A
Folding or coiling into beta pleated sheets or alpha helices using hydrogen bonds
16
Q
What type of bonds hold the tertiary structure of enzymes in place?
A
Hydrogen, ionic, and di-sulphide bonds
17
Q
What is the active site of an enzyme?
A
The part of the enzyme that carries out its function
18
Q
Why are enzymes soluble?
A
Because there are hydrophilic R groups on the outside of the molecule which mix with water
19
Q
What are extracellular enzymes?
A
Enzymes that catalyse reactions outside the cell
20
Q
How are extracellular enzymes released from the cell?
A
By exocytosis
21
Q
What are intracellular enzymes?
A
Enzymes that catalyse reactions inside cells
22
Q
What are the two types of intracellular enzymes?
A
- Enzymes in solution
- Membrane-bound enzymes
23
Q
What are intracellular enzymes in solution?
A
Enzymes that are not attached to anything inside the cell
24
Q
What are membrane-bound intracellular enzymes?
A
Enzymes that are attached to membranes and can form metabolic pathways
25
What is the lock and key model?
A model that describes how enzymes bind to substrates, where the substrate makes temporary bonds with the enzyme's active site, forming an enzyme-substrate complex.
26
What happens after the enzyme-substrate complex is formed?
The enzyme catalyses the reaction, products are released, and the active site is free to take a new substrate molecule.
27
What does enzyme specificity mean?
An enzyme is specific for its substrate and can only bind to that substrate using its active site.
28
What determines the specificity of an enzyme?
The unique shape of the active site and the types, number, and positions of the bonds made by the side chains of the amino acids in the active site.
29
Fill in the blank: An enzyme's active site is _____ for its substrate.
specific
30
True or False: The lock and key model suggests that enzymes can bind to multiple substrates.
False
31
What does the term 'complementary' refer to in the context of the lock and key model?
It refers to the shapes being equal and opposite.
32
What is the relationship between the enzyme's active site and substrate binding?
The active site has a unique shape that only fits one specific substrate.
33
What is the induced fit model in enzyme action?
Change in shape of active site, induced by entry of the substrate, allowing enzyme and substrate to bind closely to form an E-S complex
## Footnote
The induced fit model emphasizes the flexibility of the enzyme's active site.
34
What is the main difference between the induced fit model and the lock and key model for enzyme function?
In the lock and key model, the enzyme does not change shape and is not flexible; the active site is complementary in shape to the substrate
## Footnote
The lock and key model suggests a rigid interaction, while the induced fit model allows for adjustments.
35
What evidence supports the lock and key model?
Active site is complementary in shape to substrate; substrates fit into the active site groove without alteration to enzyme shape
## Footnote
This model is supported by observations of specific interactions between enzymes and substrates.
36
What evidence supports the induced fit model?
Lysozyme changes shape around the substrate molecule, distorting it to facilitate bond hydrolysis
## Footnote
Lysozyme's action demonstrates how enzymes can adapt their structure to accommodate substrates.
37
Fill in the blank: The _______ model suggests that the enzyme's active site changes shape to fit the substrate.
induced fit
38
Fill in the blank: In the lock and key model, the enzyme's active site is _______ to the substrate.
complementary
39
What happens during a reaction between two particles?
They collide and approach each other closely enough to react
## Footnote
The proximity of particles is essential for facilitating chemical reactions.
40
What is the role of lysozyme in bacterial cell walls?
Lysozyme hydrolyzes bonds in the bacterial cell wall, weakening it and causing the bacteria to burst when water is absorbed
## Footnote
This process is critical in the defense against bacterial infections.
41
What is the definition of activation energy?
The minimum amount of energy that must be put into a chemical system for a reaction to occur.
42
How do enzymes catalyse reactions?
By lowering the activation energy required to make them occur.
43
What happens to the free energy of products compared to substrates in a reaction catalysed by enzymes?
The free energy of the products is less than that of the substrates.
44
List the ways to speed up a reaction.
* Increased temperature
* Increased concentration
* Increased pressure
* Decreased activation energy
45
What is free energy (G)?
Energy available to perform work in a system.
46
What is the effect of enzymes on the activation energy without an enzyme?
Activation energy (EA) is higher without an enzyme.
47
What is the effect of enzymes on the activation energy with an enzyme?
Activation energy (EA) is lowered with an enzyme.
48
Fill in the blank: The enzyme active site has a ______ shape.
[general]
49
What occurs when the substrate binds to the enzyme?
It forms an ES complex.
50
How does the enzyme affect the bonds in the substrate?
The enzyme puts strain on the substrate and its bonds.
51
What is the result of the enzyme putting strain on the substrate bonds?
The bonds weaken and activation energy is lowered.
52
True or False: Enzymes are required for all chemical reactions to occur.
False
53
What visual representation can suggest how enzymes catalyse reactions?
A graph showing the progress of the reaction.
54
What is the formula to calculate the rate of enzyme reactions?
Rate = amount/time
55
What can be observed to calculate the rate of enzyme-catalysed reactions?
Disappearance of substrate or formation of product over time
56
What is represented on the y-axis of the graph related to enzyme reactions?
Product concentration (umol I-')
57
What is represented on the x-axis of the graph related to enzyme reactions?
Time (s)
58
What happens at the beginning of an enzyme reaction when there is an excess of substrate molecules?
Chances of successful collision between substrates and enzymes are high
59
What forms when substrates bind in the active site of an enzyme?
Enzyme-substrate complexes
60
What limits the rate of reaction when excess substrate is present?
Enzymes have a maximum turnover rate and can only work at a certain speed
61
What happens to the substrate concentration as the reaction proceeds?
There are fewer substrate molecules available and fewer successful collisions
62
What becomes the limiting factor on the rate of reaction as substrate concentration decreases?
Substrate concentration
63
What eventually happens to the substrate during the enzyme reaction?
All the substrate has been used up and no more product can be formed
64
How do you calculate the rate of product formation over a given time?
1. Find difference in product amount from beginning to end of time period
2. Divide this amount by time period for rate of product per unit time
## Footnote
This method allows for determining how quickly a reaction produces product over a specified interval.
65
What is the rate of product formation between 10 and 20 minutes at 37°C in g dm min?
0.45 g dm * min
## Footnote
The calculation is based on the difference in product amount (12.5 - 8 = 4.5) divided by the time interval (10 minutes).
66
What would be the rate of product formation in g dm ' hr?
27 g dm * hr
## Footnote
This is found by multiplying the rate per minute (0.45) by 60.
67
How do you calculate the % increase/decrease in mass?
1. Find difference in mass from beginning to end of time period
2. Divide by the initial mass
3. Multiply by 100
## Footnote
This formula helps quantify the relative change in mass over a specified time frame.
68
What was the % increase in product formation for the reaction at 37°C from 10 to 20 min?
56%
## Footnote
The calculation is based on the difference in product formation (4.5) divided by the initial mass (8), multiplied by 100.
69
How do you calculate the change in reaction rate at a given time?
Measure the gradient at that point by drawing a tangent to the curve
## Footnote
Steps: 1. Draw a tangent to the curve. 2. Connect the ends into a triangle. 3. Rate = y/x. 4. Units should be amount per unit time.
70
What is the formula for calculating rate from a tangent?
Rate = y/x
## Footnote
'y' represents the change in the dependent variable, and 'x' represents the change in the independent variable.
71
What units should be used for measuring reaction rate?
Amount per unit time
## Footnote
Commonly expressed in units like g/dm³/min.
72
What temperature was used in the experiment for the enzyme-controlled reaction?
37 °C
## Footnote
The experiment also included a temperature of 60 °C.
73
What are two factors the technician should control in the enzyme experiment?
Concentration of substrate and pH
## Footnote
Controlling these factors ensures that the effect of temperature on the reaction rate can be accurately assessed.
74
What type of graph was used to display the results of the enzyme reaction?
A graph showing concentration of product over time
## Footnote
The x-axis represents time after the start of the reaction, while the y-axis represents concentration of product in g/dm³.
75
Fill in the blank: To find the change in reaction rate, you connect the ends into a _______.
triangle
76
True or False: The technician varied the concentration of substrate during the experiment.
False
## Footnote
The technician started the reaction using the same concentration of substrate at each temperature.
77
What factors affect enzyme activity?
1. pH
2. Concentration of substrate
## Footnote
Enzymes are sensitive to changes in pH and substrate concentration, which can influence their activity.
78
How do you determine initial rates of reaction using curves?
Draw a tangent on each curve to find the initial rates of reaction.
## Footnote
This method allows for the calculation of reaction rates at specific time points.
79
What is the calculated ratio of initial rates of reaction at 60 °C to 37 °C?
3.57:1
## Footnote
The rates of reaction were calculated as 7.5 at 60 °C and 2.1 at 37 °C.
80
What is the initial rate of reaction at 60 °C?
7.5 g/min
## Footnote
This value represents the enzyme activity at the higher temperature.
81
What is the initial rate of reaction at 37 °C?
2.1 g/min
## Footnote
This value indicates a lower enzyme activity compared to 60 °C.
82
Explain the difference in initial rates of reaction at 60 °C and 37 °C.
At 60 °C, there is more kinetic energy in substrate and enzyme, leading to more frequent collisions and more enzyme-substrate complexes formed.
## Footnote
Higher temperatures increase molecular movement, enhancing reaction rates.
83
Describe the reaction rates at 37 °C between 20 and 40 minutes.
At 37 °C after 20 minutes, some substrate remains, but lower concentration slows reaction rates leading to a slowdown after 30 minutes.
## Footnote
This indicates that substrate availability affects the rate of reaction.
84
What happens to enzymes at 60 °C after a certain time?
All enzymes become denatured due to high temperatures, stopping enzyme-substrate complexes from forming.
## Footnote
Denaturation leads to a loss of enzyme activity, halting the reaction.
85
What is the effect of temperature on enzyme-controlled reactions?
Alters active site shape
## Footnote
This can lead to changes in enzyme activity and reaction rates.
86
How does the presence of inhibitors affect enzyme-controlled reactions?
Changes number of ES complexes formed
## Footnote
Inhibitors can decrease the rate of reaction by preventing substrate binding.
87
What happens to the reaction rate when the temperature is increased beyond a certain point?
Reaction no longer occurring
## Footnote
High temperatures can denature enzymes, leading to a loss of function.
88
List factors that can affect the rate of enzyme-controlled reactions.
* Temperature
* Presence of inhibitors
## Footnote
These factors can significantly influence the efficiency and speed of enzymatic reactions.
89
True or False: The shape of the active site is not affected by temperature.
False
## Footnote
Temperature changes can alter the conformation of the enzyme's active site.
90
What happens to the rate of reaction as temperature increases up to 40 degrees?
The rate of reaction increases up until 40 degrees, which is the optimum temperature.
91
What occurs to the rate of reaction after reaching the optimum temperature?
The rate of reaction decreases until it stops at 60 degrees.
92
Fill in the blank: As temperature increases, the rate of reaction increases up until _______.
40 degrees
93
What is the effect of high temperature on enzyme action?
High temperature increases kinetic energy, leading to more frequent collisions and formation of more enzyme-substrate complexes, up to optimum temperature.
94
What happens to hydrogen bonds in enzymes at high temperatures?
Weaker hydrogen bonds vibrate and break, leading to changes in the enzyme's tertiary structure.
95
True or False: The active site of an enzyme remains unchanged at high temperatures.
False
96
What changes occur to the active site when an enzyme denatures?
The active site shape and charges gradually change, making it no longer complementary to the substrate.
97
What is the consequence of an enzyme denaturing?
The enzyme can no longer form enzyme-substrate complexes and stops working altogether.
98
Give three reasons why our body temperature is maintained at 37 degrees, not 40.
* 40 degrees could denature other proteins
* Illness could denature enzymes
* Intense exercise could denature enzymes
99
What happens to the rate of reaction for every 10°C increase?
The rate of reaction doubles
## Footnote
This is a general rule observed in enzyme-catalyzed reactions.
100
Why do reactions stop at very low temperatures?
Enzymes are inactivated due to molecules having very low kinetic energy and can't form ES complexes.
101
Which is reversible: inactivation or denaturation?
Inactivation
102
What is the lowest structure of a protein that will be unaffected by denaturation?
Primary
## Footnote
The primary structure remains intact because there are no hydrogen bonds to break.
103
What is pH a measure of?
The H+ ion concentration of a solution.
104
Describe the relationship between pH and H+ ion concentration.
It is an inverse relationship; acids have a high free H+ ion concentration and therefore a low pH.
105
What effect do small pH changes around the optimum have on enzyme activity?
They cause small reversible changes in enzyme structure and reduce activity.
106
What happens to enzymes at extremes of pH change?
They undergo denaturation.
107
What affects the charges on amino acid side chains making up the active site of enzymes?
H+ and OH- ions
108
Fill in the blank: pH changes can ______ enzymes.
denature
109
What happens to enzymes at low pH?
Excess H+ ions bond to -ve charges on amino acid side chains, disrupting ionic and H bonds
## Footnote
This disruption can change the tertiary shape and active site shape of the enzyme.
110
What happens to enzymes at high pH?
Excess OH- ions bond to +ve charges on amino acid side chains, disrupting ionic and H bonds
## Footnote
This can also change the tertiary shape and active site shape of the enzyme.
111
What is the effect of disrupted ionic and H bonds on enzymes?
Changes the active site shape, preventing substrate binding and ES complex formation
## Footnote
This results in decreased enzyme activity.
112
Which enzyme is most likely found in the stomach?
Pepsin
## Footnote
Pepsin operates optimally at acidic pH, which is typical for the stomach environment.
113
Which enzyme is most likely found in the pancreas?
Trypsin
## Footnote
Trypsin operates optimally at alkaline pH, suitable for pancreatic conditions.
114
What does a point of saturation in enzyme activity indicate?
The maximum rate of reaction has been reached, and adding more substrate will not increase the rate
## Footnote
This is depicted in enzyme kinetics graphs.
115
Fill in the blank: The rate of enzyme reaction is affected by _______.
substrate concentration
## Footnote
Changes in substrate concentration can lead to varying rates of enzyme activity.
116
What is the relationship between substrate concentration and enzyme activity?
As substrate concentration increases, enzyme activity increases until it reaches a saturation point
## Footnote
Beyond this point, additional substrate does not affect the reaction rate.
117
What happens to enzymes at low pH?
Excess H+ ions bond to -ve charges on amino acid side chains, disrupting ionic and H bonds
## Footnote
This disruption can change the tertiary shape and active site shape of the enzyme.
118
What happens to enzymes at high pH?
Excess OH- ions bond to +ve charges on amino acid side chains, disrupting ionic and H bonds
## Footnote
This can also change the tertiary shape and active site shape of the enzyme.
119
What is the effect of disrupted ionic and H bonds on enzymes?
Changes the active site shape, preventing substrate binding and ES complex formation
## Footnote
This results in decreased enzyme activity.
120
Which enzyme is most likely found in the stomach?
Pepsin
## Footnote
Pepsin operates optimally at acidic pH, which is typical for the stomach environment.
121
Which enzyme is most likely found in the pancreas?
Trypsin
## Footnote
Trypsin operates optimally at alkaline pH, suitable for pancreatic conditions.
122
What does a point of saturation in enzyme activity indicate?
The maximum rate of reaction has been reached, and adding more substrate will not increase the rate
## Footnote
This is depicted in enzyme kinetics graphs.
123
Fill in the blank: The rate of enzyme reaction is affected by _______.
substrate concentration
## Footnote
Changes in substrate concentration can lead to varying rates of enzyme activity.
124
What is the relationship between substrate concentration and enzyme activity?
As substrate concentration increases, enzyme activity increases until it reaches a saturation point
## Footnote
Beyond this point, additional substrate does not affect the reaction rate.
125
What is a competitive inhibitor?
An inhibitor similar in shape to the substrate and complementary to the active site.
126
How does a competitive inhibitor function?
It binds to and blocks the active site temporarily, competing with the substrate.
127
What effect does increasing substrate concentration have on competitive inhibition?
It lessens the effect of the inhibitor as there is more chance of enzyme-substrate collision.
128
What is a key feature of non-competitive inhibition?
It prevents substrate from binding and prevents enzyme-substrate complex formation.
129
How does increasing substrate concentration affect non-competitive inhibition?
It does not decrease the effect of the inhibitor as the enzymes are effectively denatured.
130
Fill in the blank: A competitive inhibitor competes with the substrate for the _______.
active site
131
True or False: Increasing substrate concentration can outcompete a non-competitive inhibitor.
False
132
What happens to enzymes in non-competitive inhibition?
They are effectively denatured and unable to catalyze.
133
Draw a curve to illustrate the effect of adding a competitive inhibitor to a reaction. What axes should be labeled?
X-axis: substrate concentration, Y-axis: reaction rate
134
What is the temporary nature of competitive inhibition?
It binds temporarily to the active site.
135
What is the role of the active site in enzyme function?
It is where the substrate binds to facilitate the reaction.
136
What is end-product inhibition?
When a product in a series of linked reactions inhibits an enzyme from earlier in a metabolic pathway.
137
What is the purpose of end-product inhibition in metabolic pathways?
To prevent overproduction of certain chemicals, which may be toxic in large quantities, or which would be waste of energy producing.
138
What does non-competitive inhibition affect in enzyme activity?
It affects the reaction rate without altering the substrate concentration.
139
In a non-competitive inhibition graph, what is plotted on the x-axis?
Substrate concentration
140
In a non-competitive inhibition graph, what is plotted on the y-axis?
Reaction rate
141
Fill in the blank: End-product inhibition controls the _______ of cell metabolism.
rate
142
What are immobilised enzymes?
Enzyme molecules bound to an inert material, over which substrate molecules can move.
## Footnote
Immobilised enzymes can be fixed, bound, or trapped on materials like sodium alginate beads or cellulose microfibrils.
143
How are immobilised enzymes typically arranged for use?
The beads are packed into glass columns.
## Footnote
Substrate is added at the top of the column and trickles down, forming E-S complexes with enzyme active sites.
144
Why do smaller beads give a faster rate of reaction?
They have a larger surface area to volume ratio, exposing more enzyme active sites.
## Footnote
This increased exposure allows for more interactions between enzymes and substrates.
145
Why do immobilised enzymes in beads have a lower rate of reaction than those on a membrane surface?
It takes time for the substrate to diffuse into the bead.
## Footnote
Membrane surfaces allow for quicker access to enzyme active sites compared to beads.
146
List three advantages of using immobilised enzymes in industry.
* The column can be used repeatedly
* Enzymes can be easily recovered for re-use
* Enzyme does not contaminate end products, resulting in pure products.
147
True or False: Enzymes work at higher temperatures compared to inorganic catalysts.
False.
## Footnote
Enzymes work at lower temperatures, making them more economical than inorganic catalysts.
148
Fill in the blank: Immobilised enzymes have a higher _______ number compared to other catalysts.
[turn-over]
## Footnote
This refers to the rate at which an enzyme converts substrate into product.
149
What is the role of the bead in enzyme stability?
Creates a stable microenvironment, protecting enzyme from high temperature/extreme pH ranges
## Footnote
This prevents shape change that would denature the enzyme.
150
How can different enzymes be used in a single process?
Sequence of columns can be used with different enzymes with different pH and temperature
## Footnote
This allows for versatility in enzyme applications.
151
What advantage do immobilised enzymes offer in reactions?
Enzymes can easily be added or removed, allowing greater control over the reaction
## Footnote
This flexibility is crucial for optimizing industrial processes.
152
What is the primary use of immobilised lactase in milk production?
To produce lactose-free milk
## Footnote
Immobilised lactase converts lactose into glucose.
153
What happens to lactose in the milk when it flows through alginate beads?
Lactase catalyses the hydrolysis of lactose into glucose and galactose
## Footnote
This process is essential for creating lactose-free milk.
154
Fill in the blank: Immobilised lactase in the beads catalyses the hydrolysis of lactose into _______ and galactose.
glucose
155
What are the main components of a biosensor?
Analyte, molecule, transducer, display
## Footnote
These components work together to detect and display information about the analyte.
156
What do enzymes do?
Turn chemical signals into electrical ones.
157
What is the function of enzymes in detecting molecules?
Detect small amounts of important molecules.
158
What is glucose-oxidase used for?
Binds to glucose in blood samples and generates an electric current.
159
How can glucose-oxidase be utilized in diabetes management?
Used to measure glucose levels in urine.
160
What is the purpose of immobilizing enzymes on test strips?
Different strips detect different chemicals.
161
What is High Fructose Corn Syrup (HFCS)?
A sweetener made from corn, processed using enzymes.
162
What role does alpha amylase play in HFCS production?
Breaks down starch into oligosaccharides at 90 degrees.
163
What does glucoamylase do in the HFCS manufacturing process?
Breaks down oligosaccharides into glucose at 60 degrees.
164
What is the function of glucose isomerase?
Converts glucose into fructose.
165
Define oligosaccharide.
Short chain carbohydrate.
166
Define isomerase.
Enzyme that changes the structure of a molecule without changing the chemical formula.
