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A level Biology - Unit 2 > Enzymes > Flashcards

Enzymes Flashcards

1
Q

What are extracellular enzymes?

A

Enzymes that work outside the cell.

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2
Q

Give an example of an intracellular enzyme, what does it do?

A

Catalase. It catalyses the breakdown of hydrogen peroxide into oxygen and water.

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3
Q

Give two examples of extracellular enzymes?

A

Amylase and Trypsin

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4
Q

Where is amylase found and what is its function?

A

It is found in saliva. It catalyses the hydrolysis of starch into maltose.

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5
Q

Where is trypsin found and what is its function?

A

It is found in the small intestine produced by pancreatic cells. It catalyses the hydrolysis of peptide bonds making polypeptides into smaller ones.

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6
Q

What are enzymes?

A

They are biological catalysts that speed up metabolic reactions in a cell or organism.

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7
Q

What is the active site?

A

Part of an enzyme that substrate molecules bind to.

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8
Q

What is the active site’s shape based on?

A

The tertiary structure of that enzyme.

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9
Q

The active site and substrate molecules are what to eachother?

A

Complementary.

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10
Q

What is activation energy?

A

The energy required for a chemical reaction to start.

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11
Q

How do enzymes speed up reactions in the body?

A

They reduce the overall activation energy by the formation of the enzyme-substrate complex.

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12
Q

What are the two hypothesise for how enzymes work?

A

Lock and key hypothesis

Induced-Fit hypothesis.

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13
Q

Describe the lock and key hypothesis.

A

Only a specific substrate can enter the active site of an enzyme in the same way that a specific key fits into a lock.

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14
Q

Describe the induced-fit hypothesis.

A

The active site of an enzyme changes shape slightly as the substrate molecule enters.

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15
Q

What are the four factors that affect enzyme activity?

A

Temperature
pH
Enzyme concentration
Substrate concentration

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16
Q

How does an increase in temperature affect the rate of an enzymes activity?

A

More heat means more kinetic energy so particles move faster and collide more frequently. This increases the chance of successful interactions between substrate and active site.

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17
Q

How is an enzyme denatured by high temperatures?

A

The vibrations become too strong and cause the bonds holding the active site to break. This changes the shape of the active site, so it can no longer do its job.

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18
Q

What does the temperature coefficient, Q10, mean?

A

It shows how much the rate of reaction changes when the temperature is raised by 10 *C

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19
Q

What is it called when an enzyme and subtracted bind together?

A

Enzyme-substrate complex.

20
Q

What is the optimum pH value of an enzyme?

A

The pH at which enzymes work their best.

21
Q

What pH does the enzyme Pepsin work best at?

A

pH 2 (same as stomach acid)

22
Q

How are enzymes denatured by pH levels?

A

pH too high/low means that the H+ and OH- ions interfere with the bonds holding the tertiary structure together.

23
Q

How does enzyme concentration increase rate of reaction?

A

Increases the chance of successful collisions between substrate and enzyme as there are more free active sites to be filled.

24
Q

How does substrate concentration increase the rate of reaction?

A

More substrates means more collisions as more active sites are being filled.

25
Q

What is saturation point?

A

The point when all active sites are full so adding more substrates won’t make a difference to the rate of reaction.

26
Q

What are intracellular enzymes?

A

Enzymes that work inside the cell.

27
Q

What are inhibitors?

A

Molecules that prevent enzymes from catalysing reactions.

28
Q

What are the two types of enzyme inhibitors?

A

Competitive and non-competitive.

29
Q

What is competitive inhibition?

A

When the inhibitor compete with the substrate molecules for the active site.

30
Q

What shape are competitive inhibitors?

A

They have a similar shape to the substrate molecule.

31
Q

How do you competitive inhibitors decrease the rate of reaction?

A

They bind to the enzyme and block the active site which stops the substrate from entering it.

32
Q

What is non-competitive inhibition?

A

When the inhibitor binds to the allosteric site making the active site change shape.

33
Q

How do non-competitive inhibitors decrease the rate of reaction?

A

They change the shape of the active site which prevents substrate molecules from binding to it.

34
Q

When is an inhibitor reversible?

A

When there are weak bonds between the enzyme and inhibitor it means it can be removed. Binds loosely.

35
Q

When is an inhibitor non-reversible?

A

When there are strong covalent bonds between the enzyme and inhibitor it means it cannot be removed easily. Binds tightly.

36
Q

What is end-product inhibition?

A

When the product of a reaction acts as an inhibitor to the enzyme that produces it.

37
Q

What is an anabolic reaction?

A

Chemical reactions that are required for growth and build up of organisms

38
Q

What are catabolic reactions?

A

Chemical reactions that breakdown large molecules, like glucose, releasing energy that is required for all processes. Usually done by digestion.

39
Q

What is metabolism?

A

The sum of all the different reactions and reaction pathways that happen in a cell.

40
Q

What are cofactors and coenzymes?

A

A non-protein component required by enzymes to carry out their function properly.

41
Q

Give an example of a cofactor?

A

Minerals and ions like Cl- Zn2+ Ca2+

Chloride ions are cofactors for Amylase.

42
Q

Give an example of a coenzyme?

A

Vitamin B5 used for coenzyme A.

43
Q

What is the main difference between cofactors and coenzymes?

A

Cofactors are in organic and coenzymes are organic.

44
Q

What are prosthetic groups?

A

Like cofactors, they are needed by enzymes to carry out their function.

45
Q

Give an example of a prosthetic group?

A

Zn2+ ions are a prosthetic group for carbonic anhydrase (an enzyme used to catalyse the production of carbonic acid from water and carbon dioxide.)

46
Q

What is it about prosthetic groups, that is different from cofactors?

A

They bind tightly and become a permanent part of the enzyme.

A level Biology - Unit 2 (17 decks)

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