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Year 1 biology > 2.1.4 enzymes > Flashcards

2.1.4 enzymes Flashcards

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1
Q

what molecule are enzymes
2.1.4(a)

A

Enzymes are protein molecules.

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2
Q

what is an enzyme
2.1.4(a)

A

Enzymes are biological catalysts that reduce the activation energy needed for reactions in living organisms

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3
Q

how is lowering the activation energy useful
2.1.4(a)

A

This means that metabolic reactions can proceed at the rate needed to sustain life, even at quite low temperatures – e.g. human body temperature, 37oC.

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4
Q

how are higher temperatures detrimental to the enzyme
2.1.4(a)

A

Higher temperatures would denature the enzymes and so enzymes are crucial to allow life to exist at lower temperature

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5
Q

what do catalysts do
2.1.4(a)

A

Catalysts reduce activation energy to speed up reactions, and remain unchanged at the end of a reaction

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6
Q

what can a small number of enzymes do
2.1.4(a)

A

A small number of enzyme molecules can catalyse the conversion of a huge number of substrate molecules into product
-this means the enzyme doesn’t run out until it gets damaged

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7
Q

what is the function in every living cell catalyzed by
2.1.4(a)

A

Virtually every function in a living cell is catalysed by enzymes, for example respiration and photosynthesis

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8
Q

how are enzyme controlled reactions responsible for the structure of an organism
2.1.4(a)

A

Enzyme-controlled reactions are also responsible for the structure of an organism, because enzymes are involved in development, for example by synthesis of fibrous proteins like collagen and keratin.

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9
Q

what does intracellular mean
2.1.4(b)

A

Intracellular means “inside a cell”

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10
Q

where do intracellular enzymes catalyse reactions
2.1.4(b)

A

Intracellular enzymes catalyse reactions that take place inside cells, in the cytoplasm, or inside one of the organelles e.g. mitochondria or chloroplasts

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11
Q

how many metabolic reactions can take place at the same time inside cells
2.1.4(b)

A

There may be up to 1000 metabolic reactions taking place at the same time inside a cell.

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12
Q

what is an example of an intracellular enzyme and where is it found
2.1.4(b)

A

Catalase is an intracellular enzyme. It is found in nearly all living organisms that are exposed to oxygen

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13
Q

what is the function of catalase
2.1.4(b)

A

Its function is to break down the molecule hydrogen peroxide, H2O2, which is a toxic by-product of metabolic reactions including respiration.

2H2O2 → O2 + 2H2O

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14
Q

where is catalase found
2.1.4(b)

A

In eukaryotic cells, catalase is found inside small vesicles called peroxisomes

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15
Q

what type of structure does catalase have
2.1.4(b)

A

Catalase has a quaternary structure. It consists of four polypeptide chains

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16
Q

what is each polypeptide chain bound to
2.1.4(b)

A

each of which is bound to a prosthetic group. The prosthetic groups in catalase are iron-containing haem groups that allow catalase to catalyse the reaction of H2O2.

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17
Q

what does extracellular mean
2.1.4(b)

A

Extracellular means “outside a cell

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18
Q

how are extracellular enzymes made
2.1.4(b)

A

Extracellular enzymes are made by cells and then secreted to the outside of the cell by exocytosis

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19
Q

what is the function of extracellular enzymes
2.1.4(b)

A

Their function is to catalyse reactions that take place outside of cells.

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20
Q

what is amylase
2.1.4(b)

A

amylase is a digestive enzyme that hydrolyses amylose into maltose

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21
Q

what is amylase made by
2.1.4(b)

A

It is made by cells in the salivary glands and secreted into the saliva in the mouth. It is also made by cells in the pancreas, and secreted into the small intestine.

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22
Q

where is trypsin made and where is it secreted
2.1.4(b)

A

Trypsin is made by cells in the pancreas and secreted into the small intestine

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23
Q

what is the role of trypsin
2.1.4(b)

A

Trypsin hydrolyses peptide bonds to break down proteins into smaller polypeptides.

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24
Q

what specific area of the active site to substrate molecules fit into
2.1.4(c)

A

Substrate molecules fit into a specific area of the enzyme molecule called the active site

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25
why can substrates fit the active site 2.14(c)
Substrates can fit the active site because the tertiary structure of the active site is complementary to its substrate,
26
what happens once the substrate is bound to the active site 2.1.4(c)
Once the substrate is bound to the active site, the enzyme catalyses the reaction of the substrate.
27
what would happen if the tertiary structure of the active site changed 2.1.4(c)
If the tertiary structure of the active site changed, then the substrate would no longer fit, and so the enzyme would not be able to catalyse the reaction, and the reaction would stop.
28
what does the lock and key hypothesis describe
that the tertiary structure of the active site is complementary to its substrate the active site and substrate fit perfectly together
29
what is the lock and key hypothesis
substrate molecules fit into the enzymes active site and temporary hydrogen bonds hold the two together forming an enzyme-substrate complex the enzyme catalyses the reaction of the substrate forming products the products temporarily stay bonded to the active site which is called an enzyme product complex the products aren't complementary to unbind and are released the enzyme is not changed during the reaction
30
how does the lock and key hypothesis lower the activation energy
it holds the substrates in the correct orientation lowering the activation energy needed for the reaction to take place
31
what is the induced fit hypothesis
when the substrate binds to the active site it induces a conformational change in the tertiary structure of the active site the substrate binds to the active site which forms an enzyme substrate complex the enzyme catalyses the conversion of the substrate, forming products. The products temporarily stay bonded to the active site-this forms an enzyme product complex the products aren't complementary to the active site so they unbind and are released the enzyme is not changed during the reaction
32
how does induced fit hypothesis reduce the activation energy
when the shape of the active site changes is puts strain on the substrate molecules and weakens the bonds in the substrate so they don't require as much energy to break therefore the activation energy has been reduced
33
what is activation energy
the energy required to break the chemical bonds in the reactants and start a reaction
34
how would you reach activation energy in a lab setting
this would be achieved by increasing the temperature, such as by using a Bunsen burner. We can’t do this in living organisms, as high temperatures denature proteins and enzymes that living organisms are made of.
35
draw the graph for pH
in booklet
36
what is the optimum pH
the pH in which enzymes work at there maximum rate
37
Why above or below the optimum pH does rate of reaction decrease
because pH involves H+ or OH- pHs above and below optimum affect ionic and hydrogen bonds in the tertiary structure of the enzyme these bonds rely on charges so are affected by nearby H+ and OH- ions this causes the tertiary structure of the enzyme to change this causes the enzyme to denature
38
draw the graph for temperature
in booklet
39
what is optimum temperature
temperature at which enzyme works at its maximum rate
40
what happens above the optimum temperature
high temperatures break bonds in tertiary structure of the enzyme eg-ionic, disulphide and hydrogen the tertiary structure of active site changes this causes the enzyme to denature
41
what is Q10
how many times the rate would increase if temperature increased by 10 degrees Celcius R2/R1
42
what happens to the rate of an enzyme controlled reaction when temperature increases by 10 degrees celcius
The rate of an enzyme-controlled reaction doubles when temperature increases by 10o
43
draw the graph for enzyme concentration
in booklet
44
what happens as enzyme concentration increases
when enzyme concentration increases so does the amount of available active sites this means more enzyme substrate complexes the rate of reaction increases until the substrate becomes the limiting factor
45
draw the graph for substrate concentration
in booklet
46
what is the effect on increasing substrate concentration
As substrate concentration increases, the rate of reaction increases because active sites are more likely to collide with substrate molecules · Eventually, the enzymes cannot work any faster: as soon as products are released, the next substrate molecule immediately binds to the active site · The enzymes become saturated · The maximum rate of an enzyme when excess substrate provided is called Vmax (maximum velocity
47
what must you do when investigating the rate of enzyme or substrate concentration on enzyme-controlled reaction 2.1.4(dii)
you must prepare a suitable range of solutions of different concentrations.
48
what is a serial dilution and how could you make one and draw the table 2.1.4(dii)
in booklet
49
how do you calculate rate of an enzyme controlled reaction 2.1.4(dii)
amount of product formed/amount of substrate use time
50
1/1how do you calculate rate if you haven't been told how much substrate is used or product formed 2.1.4(dii)
1/time -or if numbers are too small to plot on a graph 1000/time
51
how to calculate initial rate of enzyme activity 2.1.4(dii)
draw a tangent at T=0
52
what does accurate mean 2.1.4(dii)
close to the true value
53
How do you identify the optimum temperature 2.1.4(dii)
-when you conduct an experiment to identify the optimum temperature the results might not be accurate (close to the true value) due to the intervals of the IV so you should test temperature/pH eg-between 30 and 50 to be certain where the optimum temperature lies
54
How can the experiment or set of results be valid 2.1.4(dii)
1. if the IV caused the change in the DV 2. if the IV is the ONLY thing that cause the change in the DV
55
what are practical precautions 2.1.4(dii)
steps taken in order to ensure the validity of your experiment
56
How do you prove the Iv is the only thing affecting the DV 2.1.4(dii)
we redo the experiment without any enzyme this is called experimental control
57
what are controlled variables 2.1.4(dii)
other variables that could cause a change in the DV that need to be controlled
58
what is standard deviation 2.1.4(dii)
it is a measure of how spread out the results are around the mean value
59
what does it mean if standard deviation is small 2.1.4(dii)
repeats are close to the mean meaning data is highly repeatable vice versa for large
60
how is standard deviation better than range 2.1.4(dii)
it measures the spread of data and accounts every single value so can account for anomalies
61
how is standard deviation shown on a graph 2.1.4(dii)
using error bars
62
what is a coenzyme 2.1.4(e)
small organic molecule not made of protein
63
how can coenzymes assist with enzyme function 2.1.4(e)
may temporarily bind to enzyme to assist with enzyme function
64
what is an example of a coenzyme 2.1.4(e)
NAD-coenzymes for enzymes involved in respiration
65
what is NAD made out of 2.1.4(e)
two nucleotides joined by a phosphodiester bond its organic but not a protein molecule
66
how do our cells make coenzyme 2.1.4(e)
using vitamins from the food we eat EG-b3 makes NAD
67
what is a cofactor 2.1.4(e)
small inorganic molecule not made of protein not bonded to the enzyme but is needed for its function
68
what is the named example of a cofactor 2.1.4(e)
cl-
69
how does amylase work 2.1.4(e)
cl- temporarily binds to amylase causing a conformational change in the shape of amylase this makes it easier for the substrate amylose to bind to the enzyme amylase this means that amylase can now catalyse the hydrolysis of amylose into maltose
70
what is a prosthetic group 2.1.4(e)
a non-protein component that is permanently covalently bonded to the protein that helps the protein carry out its function
71
what is the prosthetic group for carbonic anhydrase 2.1.4(e)
Zn2+ which is permanently covalently bonded to its active site
72
where is carbonic anhydrase found 2.1.4(e)
in the cytoplasm of red blood cells
73
what does carbonic anhydrase do + equations 2.1.4(e)
it catalyses the conversion of co2 + h20 into carbonic acid co2 + h2o(reversible reaction sign)->h2co3
74
what is this reaction important for 2.1.4(e)
the transport of co2 around the body
75
what is an inhibitor 2.1.4(f)
molecule that reduces the activity of an enzyme
76
what is competitive inhibition 2.1.4(f)
Competitive inhibitors are molecules that have a similar shape to the substrate for an enzyme. · The competitive inhibitor binds to the active site so the substrate cannot bind · The substrate and the competitive inhibitor “compete” with each other for access to the active site · If the substrate concentration is very high, then the substrate is more likely to collide with the active site than the competitive inhibitor is · The effects of a competitive inhibitor can be overcome by high substrate concentrations o This can be shown on a graph – the enzyme can still reach Vmax at very high substrate concentrations
77
graph for competitive inhibition 2.1.4(f)
in booklet
78
how does a non-competitive inhibitor work 2.1.4(f)
Non-competitive inhibitors do not bind to the active site, and so do not compete with substrate molecules. · Non-competitive inhibitors bind to allosteric sites, which are regions of enzyme molecules other than the active site · When the non-competitive inhibitor binds to the allosteric site it causes a conformational change, which changes the tertiary structure of the enzyme’s active site · The active site is no longer complementary to the substrate · The substrate and active site can no longer bind to each other – the enzyme-substrate complex cannot form
79
what do non-competitive inhibitors reduce 2.1.4(f)
· Non-competitive inhibitors reduce the concentration of active enzymes o Therefore non-competitive inhibitors reduce the Vmax of an enzyme · This cannot be overcome by adding more substrate, as this would just lead to the remaining active enzymes becoming saturated
80
draw graph for non-competitive inhibition 2.1.4(f)
in booklet
81
how does poison and medicinal drugs work 2.1.4(f)
they are enzyme inhibitors
82
what is cyanide 2.1.4(f)
Cyanide is a metabolic poison that is fatal to almost every organism. It is a non-competitive inhibitor of an enzyme involved in respiration.
83
how are antriretroviral drugs used 2.1.4(f)
Antiretroviral drugs are used to treat HIV and can prevent HIV from ever developing into the fatal condition AIDS. Antiretroviral drugs are competitive inhibitors of HIV enzymes. They prevent the HIV virus from reproducing inside infected cells.
84
what is a non-reversible inhibitor 2.1.4(f)
Some inhibitors bind permanently to the active or allosteric site, permanently inhibiting the enzyme molecule they are bound to
85
what is a reversible inhibitor 2.1.4(f)
Some inhibitors only bind temporarily, and can be removed
86
What is end-product inhibition 2.1.4(f)
the final product in a series of reactions inhibits an enzyme from an earlier step in the sequence.
87
what does end-product inhibition ensure 2.1.4(f)
End-product inhibition ensures that the amount of an essential product inside a cell is always tightly regulated.
88
what happens if there is too much or too little product 2.1.4(f)
If product levels build up, the product inhibits the reaction pathway and hence decreases the rate of product formation. If product levels drop, the reaction pathway will not be inhibited, and the rate of product formation will increase.

Year 1 biology (25 decks)

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