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BIOLOGY OCR A > 2.4 Enzymes > Flashcards

2.4 Enzymes Flashcards

1
Q

What are enzymes

A

Globular proteins that are biological catalysts, that interact with substrates

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2
Q

What are the chemical reactions for growth called. What are the chemical reactions for breaking down called?

A

Building up - Anabolic
Breaking down - Catabolic

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3
Q

What is metabolism

A

Sum of all the different chemical reactions happening in the cell

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4
Q

What is a Vmax

A

Enzymes can only increase the rate of reaction up to a certain point

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5
Q

What conditions effect enzyme action

A

Temperature, pressure, pH, concentration (of substrate and enzyme)

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6
Q

What happens to enzyme action when temperature and pressure increase

A

molecules have higher kinetic energy, resulting in more frequent successful collisions, increasing rate of reaction

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7
Q

What is the specificity of an enzyme

A

An enzyme can only catalyse one reaction

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8
Q

What is the activation energy of a reaction

A

Energy needed to be supplied for a reaction to start

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9
Q

What do enzymes do in terms of the activation energy

A

Enzymes help molecules collide successfully, reducing activation energy

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10
Q

Explain the lock and key hypothesis

A

Only a specific substrate can lock into the active site of the enzyme. When the substrate binds to an enzyme, The R groups interact, holding the substrate in place, a enzyme substrate complex is formed. Substrate reacts, forming an enzyme-product complex, products are released, enzyme remains unchanged.

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11
Q

Explain the induced fit-hypothesis

A

Enzyme changes shape slightly when substrate enters,

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12
Q

Why did the induced fit hypothesis become created

A

Initial interaction between enzymes and substrate is weak, however, this changes the enzyme’s tertiary structure, strengthening the binding and lowering activation energy

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13
Q

What are intracellular enzymes. What are extracellular enzymes

A

Intra - Enzymes in the cell.

Extra - Enzymes that work outside the cell, break down large molecules, so that they can enter the cell

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14
Q

Explain starch breaking down

A

Amylase breaks starch into maltose.
Maltose is broken down into glucose by maltase

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15
Q

Where is Amylase produced

A

Amylase is produced in salivary glands and pancreas, and released in pancreatic juice and small intestine

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16
Q

Where is maltase present

A

Small intestine

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17
Q

How does temperature impact enzyme action?

A

Increasing temperature increases the kinetic energy of particles, so collide successfully more frequently

18
Q

What is the temperature coefficient (Q10)

A

How much the Rate of reaction increases with a 10oc rise

19
Q

What does denatured means

A

Enzyme’s active site changes shape, meaning it is no longer complementary to the substrate

20
Q

What happens if temperature increases too much

A

Enzyme becomes denatured, Temperature coefficient does not apply any more, as the enzymes has become denatured

21
Q

What is the optimum temperature

A

temperature at which enzyme activity is at it’s highest

22
Q

What adaptations have enzymes adapted if they are in temperature extremes

A

Cold - more flexible structure
Warm - les flexible structure (more bonds)

23
Q

What is the impact of pH on enzyme action

A

pH above or below the optimum pH causes the active site to change, but if the pH returns, then active site resumes normal shape - renaturation
Significant pH change causes irreversible denature

24
Q

What is the impact of substrate and enzyme concentration on enzyme action

A

Higher concentration of either increases rate of reaction
Substrate - higher collision rate with enzyme
Enzyme - increases available active sites
RoR increases to maximum Vmax - all active sites are occupied

25
Q

What is the limiting factor

A

Factor that prevents more reactions occurring

26
Q

Why is it important to control enzyme action

A

So that reactions do not occur too fast, reactions can be multi-step

27
Q

how can enzymes be activated?

A

Cofactors

28
Q

How can enzymes be inhibited?

A

inhibitors

29
Q

What are the two types of inhibitors

A

Competitive, non-competitive

30
Q

What are competitive inhibitors

A

Molecule with similar shape to the substrate fit into active site, blocking the substrate from entering the active site, so enzyme cannot carry out it’s function, slowing down rate of reaction

31
Q

What are the impacts of competitive inhibitors

A

Reduces rate of reaction, without changing the Vmax, if substrate concentration is increased, there will be much more substrate than inhibitors, so Vmax can be reached

32
Q

Give an example of a competitive inhibitors

A

Statins - CI of an enzyme used to synthesize cholesterol
Aspirin - Inhibits the active sites of COX enzymes preventing chemicals for pain/fevers

33
Q

What are non competitive inhibitors?

A

Inhibitor binds to an enzyme at a location other then the active site, causing the tertiary structure of an enzyme, resulting in the active site no longer having a complementary shape, so the enzyme cannot carry out it’s function, they can be reversible or irreversible

34
Q

What is the effect of non-competitive inhibitors on enzyme activity

A

Increasing the concentration of an inhibitor decreases rate of reaction, increasing enzyme or subsrate concentration will not overcome inhibitor

35
Q

What is an example of an irreversible non-competitive inhibitor

A

Organophosphates - insecticides, inhibit acetyl cholinesterase, (enzyme necessary for nerve impulses)

36
Q

What is end product inhibition.

A

Enzyme inhibition occurs when the product of a reaction acts as an inhibitor, negative feedback

37
Q

What are cofactors

A

non protein ‘helper’ components

38
Q

What are inorganic cofactors

A

Obtained via the diet, minerals, vitamins

39
Q

What are prosthetic groups

A

Cofactors and are required by some enzymes, tightly bound to the enzyme, forming a permanent feature

40
Q

What is precursor activation

A

Need to undergo a change in shape to be activated, through the addition of a cofactor or coenzyme

BIOLOGY OCR A (6 decks)

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