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AS level - Biology > M2- Chapter 4 - Enzymes > Flashcards

M2- Chapter 4 - Enzymes Flashcards

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1
Q

What is metabolism

A

The sum of all the different reactions and reaction pathways happening in a cell or an organism

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2
Q

What is Vmax

A

Enzymes can only increase the rates of reaction up to a point. This is called Vmax.

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3
Q

What is the specificity of an enzyme

A

Enzymes can only catalyse 1 reaction, and hence they only accept that one substrate.

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4
Q

What are enzymes

A

Biological catalysts

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5
Q

How do enzymes help molecules?

A

They lower the activation energy needed.
by:
- Lock and key hypothesis
- Induced Fit hypothesis

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6
Q

Lock and Key hypothesis

A

The active site is an area within the tertiary structure that has a shape that is complementary to the shape of the substrate. It creates an enzyme-substrate complex.

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7
Q

How does the lock and key hypothesis lower the activation energy

A

The substrate is held in such a way that atoms are close enough to react. The R-Groups create a temporary bonds between the substrate by the active site.

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8
Q

Induced Fit hypothesis

A

The idea that the active site actually changes shape slightly to fit the substrate.
The weak interactions between the substrate and the enzyme rapidly induces changes in the enzyme’s tertiary structure that strengthens the bonding and puts strain on the substrate molecule.
Hence, it weakens a particular bond in the substrate, lowering the activation energy.

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9
Q

What is an extracellular enzyme

A

They work outside the cells that make them.

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10
Q

How are nutrients usually found?

A

In the form of polymers (polymers and polysaccharides)

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11
Q

Examples of intracellular enzymes:

A

Catalase

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12
Q

Examples of intracellular enzymes:

A

Amylase and Trypsin

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13
Q

How does temperature affect enzymes

A

increase KE
increase particles moving faster
increase successful collisions
increase the rate of the reaction

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14
Q

What is the temperature coefficient (Q10)

A

How much the rate of a reaction increase with a 10 degrees rise in temperature. (Usually 2 for an enzyme-controlled reactions)

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15
Q

What happens when an enzyme denatures due to temperature

A 
increase temperature 
increase vibration 
increase the bond strain and they break 
increase changing of tertiary structure
active site changes
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16
Q

Enzymes in cold temperatures

A

they are more flexible structures, meaning they are less stable. This means small temperatures changes will denature them.

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17
Q

Enzymes in hot temperatures

A

They have more bonds (especially hydrogen and disulfide bonds). Hence, they are a lot more stable and resistant to changes in temperature.

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18
Q

A change in pH means

A

Change in H+ ion concentration

19
Q

Increase H+ conc means

A

Low pH (acidic)

20
Q

Decrease H+ conc means

A

High pH (alkaline)

21
Q

Renaturation

A

Small changes with pH concentration can cause the active site to change, but if the pH is returned, the active site can go back to its original shape.
However, if the pH is significantly beyond the optimum temperature, the enzyme might denature permanently.

22
Q

How does a change in pH affect the active site?

A

Hydrogen ions can interact with the polar and charged R-Groups, and hence change the tertiary structure of the enzymes.
Increasing Hydrogen ions means increase bonds breaking.

23
Q

Increasing the substrate or enzyme concentration means what

A

The rate of the reaction will continue to increase till Vmax, and when one of the factors becomes a limiting factor.

24
Q

What is an enzyme

A

A biological catalyst

They are proteins that speed up metabolic reactions

25
Q

How to check the reliability of data

A

Repeat experiments
Find the mean or standard deviation
Identify any anomalous results
Compare results

26
Q

How to measure the change in concentration as a reaction proceeds?

A 
Take samples at a range of temperatures
Remove samples 
Heat with Benedict’s solution 
Change to colour to brick red
Remove precipitate and filter
Calibrate using plain water 
Use a red filter 
Read the transmission 
Using a known concentration to transmission calibration curve
Read off the concentration
27
Q

Describe how an antibiotic- resistant population could develop

A

Mutation
Resistant ones survive
Alleles passed down to offspring
Carries over generations

28
Q

Explain the induced-fit hypothesis of breaking molecules

A 
What is the substrate?
Substrate fits into active site 
Active site changes shape 
To fit the substrate better
 Gets more bonds 
Forms an ESC
Puts strain on the molecule to break 
The activation energy is reduced 
Shape of active site changes again once the products have left
29
Q

Explain how the an enzyme breaks down a substrate

A

The substrate is complimentary to the active site
Substrate enters the active site
The enzyme changes shape to fit the substrate
An ESC is formed
Straining of bonds
Substrate leaves the enzyme’s active site

30
Q

cofactor

A

a non-protein substance that allows some enzymes to work

31
Q

inorganic cofactors

A

they held the substrate bind to the enzymes, but they don’t directly participate
They aren’s used up at all.

32
Q

Example of inorganic cofactors

A

Chlorine for amylase.

33
Q

Coenzymes

A

Organic cofactors
They do participate in the reactions
They are constantly being changed and they act as carriers moving chemical groups that are continuously recycled.

34
Q

What is a prosthetic group

A

A cofactor that is tightly bound to an enzyme

35
Q

example of coenzymes

A

Vitamins

36
Q

Example of a prosthetic group

A

Zn ions for carbonic anhydrous.

They are a permanent group of the enzyme’s active site.

37
Q

Competitive inhibitors

A

They are very close and similar to the shape of the substrate but not identical.
No reaction occurs, the active site is only blocked.
Generally reversible

38
Q

Non-competitive inhibitors

A

Completely different shape to the active site
But it joins the enzyme somewhere else (at an allosteric) and causes the active site to change.
So the reaction cannot go on.

39
Q

Explain the graph for the types of inhibitors

A

Competitive ones reach the top of the plateau but they take more time.
Non-competitive ones don’t even reach the plateau, but they do reach their own plateau at the same rate.

40
Q

Reversible reaction- inhibitors

A

Competitive inhibitors

There are weaker ions/ hydrogen bonds

41
Q

Non-reversible reaction- inhibitors

A

Non-competitive inhibitors.

They have covalent bonding

42
Q

Drugs

A

An antiviral drugs- reverse transcriptase inhibitor prevents viral DNA from replicating.
Penicillin inhibits transpeptidase, which forms the protein to synthesise bacterial cell walls.

43
Q

Metabollic poisons

A

Cyanide- non-competitive inhibitors of cytochromec oxidase.
Arsenic- Non-competitive inhibitors of pyruvate dehydrogenase.
Malonate- competitve inhibitor of succinate dehydrogenase.

AS level - Biology (12 decks)

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