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Biology > Module 2: Foundations In Biology Enzymes > Flashcards

Module 2: Foundations In Biology Enzymes Flashcards

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1
Q

What is an enzyme

A

Biological catalyst

Globular protein that catalyse reactions at a cellular level and whole organism level affecting structure and function of an organism

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2
Q

How many polypeptide chains does an enzyme have??

A

1

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3
Q

Why can an enzyme not form a quaternary structure??

A

Because it only has one polypeptide chain

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4
Q

What structure do enzymes have??

A

Tertiary structure

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5
Q

What is the polypeptide chain in enzymes made of??

A

Amino acids joined by peptide bonds

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6
Q

Intercellular enzyme action

A

Action within a cell

Can be fixed within membranes (e.g. chloroplast)

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7
Q

Action of DNA Polymerase

A

Acts within nucleus for DNA replication before cell division

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8
Q

Action of catalase

A

Breaks down hydrogen peroxide

A waste product of metabolism which is very toxic and needs to be rapidly broken down within cells into o2 and water

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9
Q

Extra cellular enzyme function

A

Enzyme action outside of a cell

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10
Q

Function of amylase

A

Digests starch into maltose which is then digested into glucose in the duodenum by Maltase

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11
Q

Catabolic enzymes

A

Breaking down polymers

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12
Q

Example of catabolic enzyme

A

Proteins are digested into amino acids

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13
Q

Anabolic enzymes

A

Build up reactions

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14
Q

Example of an anabolic reaction

A

Starch is synthesised from alpha helix

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15
Q

Why are enzymes specific for a substrate??

A

due to their active site
Which has a specific shape
Is complementary to the substrate

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16
Q

What is the active site??

A

Particular area of enzyme molecule

Composed of small number of amino acids within the polypeptide

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17
Q

What is the effect of enzymes on activation energy??

A

Enzymes lower the activation energy required for a reaction to occur

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18
Q

Lock and key hypothesis

A

Theory of enzyme action in which the enzymes active site is complimentary to the substrate molecule

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19
Q

Induced fit hypothesis

A

Theory of enzyme action in which the enzyme’s active site changes shape to fit the substrate molecule more closely as it binds to it

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20
Q

What happens to the activity of enzymes as temperature increases

A

Activity of enzyme increases due to the enzyme and substrate having more kinetic energy

This increases the chances of successful collisions which helps to form more enzyme substrate complexes

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21
Q

What is the optimum temperature for enzymes

A

37-40 degrees

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22
Q

What is the optimum temperature definition

A

The temperature at which the highest rate of enzyme activity occurs

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23
Q

What is the optimum temperature of bacteria in thermal vents??

A

Around 70 degrees

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24
Q

What is the optimum temperature of organisms living in the arctic

A

5 degrees

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25
Q

What are physiological adaptations

A

Processes that take place within the body of the organism

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26
Q

What are anatomical adaptions??

A

Physical features internal or external

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27
Q

What are behavioural adaptations??

A

The way an organism acts

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28
Q

In a hot environment how is the structure of an enzyme adapted??

A

They have more bonds in their tertiary structure

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29
Q

What is the effect of a 10 degree rise in temperature

A

Doubles the rate of reaction

30
Q

Up to the optimum what is the general value of Q10

A

2

31
Q

What is the effect on the bonds when heat is applied above the optimum temperature to the enzymes?

A

Heat makes molecules vibrate as they have more kinetic energy

Puts strain on weak hydrogen bonds and ionic bonds and these bonds may break

32
Q

What happens when the bonds break in the tertiary structure of the enzymes

A

Tertiary structure eventually lost

Active site changes and no longer complimentary to the substrate

This is known as denaturing and activity of the enzyme is lost

33
Q

What happens to Q10 above the optimum temperature?

A

Above the optimum temperature Q10 does not apply

34
Q

Why is the rate of reaction slower when the temperature is below the optimum rate of reaction

A

Fewer collisions and fewer enzyme substrate complexes formed

35
Q

Do enzymes denature at low temperatures??

A

Enzymes don’t denature at low temperatures they are just less active

36
Q

What is the effect of low pH on enzymes??

A

Lots of H+ ions present

Positive charge can interfere with the hydrogen bonds and ionic bonds between the R groups of amino acids

This can change the active site which causes the denaturing of the enzymes

37
Q

What happens if the pH changes the charge on the amino acids at the active site

A

The properties of the active site change and the substrate can no longer bind

38
Q

What is the typical optimum pH of an intracellular enzyme??

A

6.5

39
Q

What happens to rate of reaction as the substrate concentration rises?

A

Rate of reaction increases because there are more substrate molecules to react

Free active sites so more collisions occur and more enzyme substrate complexes form

40
Q

What happens as the active sites become occupied

A

The enzyme is saturated and the rate plateaus

Rate of reaction remains the same (known as V max)

41
Q

What happens to the rate of reaction as the enzyme concentration increases??

A

Rate of reaction increases as there are more active sites available

More reactions occur between the substrate and the enzyme forming more enzyme substrate complexes

42
Q

What is an inhibitor

A

Any substance that slows down or stops and enzyme catalysed reaction by affecting the enzyme in some way

43
Q

What are the two types of inhibitors

A

Competitive inhibitors and non competitive inhibitors

44
Q

What is the shape of a competitive inhibitor

A

Has a similar shape to that of the substrate molecule

45
Q

How does the shape of the competitive inhibitor affect the action of the substrate

A

Similar shape so they occupy the active sites

They form enzyme-inhibitor complexes

Prevents the substrate from entering the active site to form an enzyme substrate complex

46
Q

Why do enzyme-inhibitor complexes not lead to the formation of products

A

Because the inhibitor is not identical to the substrate

The part of their shape that binds to the active site is similar

47
Q

What does the level of inhibition by a competitive inhibitor depend on?

A

The concentrations of inhibitors and substrates

48
Q

What happens to the level of inhibition with competitive inhibitors when the number of substrate molecules is increased

A

Level of inhibition decreases because a substrate molecule is more likely to collide with the active site than an inhibitor molecule

49
Q

Tempering effect of competitive inhibitors

A

Do not bind permanently to the active site

Bind for a short period of time and then leave

Removal of the inhibitor from the reaction mixture leaves the enzyme molecule unaffected

50
Q

Why is antifreeze toxic??

A

Contains ethylene glycol

In the the body this is broken down by alcohol dehydrogenase to oxalic acid which is extremely toxic

51
Q

Why is a person given alcohol intoxication when they have antifreeze poisoning??

A

Ethanol is a competitive inhibitor to alcohol dehydrogenase

Ethylene glycol is not broken down into oxalic acid

So therefore there is no toxicity and death

52
Q

Action of non-competitive inhibitors

A

Do not compete with substrate molecules for a place in the active site

53
Q

Where do non competitive inhibitors bind to??

A

Molecules attach to the enzyme molecule in a region away from the active site

54
Q

What effect does the attachment of non competitive inhibitors have on enzymes

A

Changes the tertiary structure of the enzyme molecule leading to the shape of the active site changing

55
Q

After the non competitive inhibitors have attached to the enzyme what is the effect of the active site and collisions??

A

Active site is no longer complimentary to the substrate

Enzyme substrate complex cannot form and the reaction rate decreases

56
Q

What is the effect of non competitive inhibitors on the v MAX

A

VMax = lower

57
Q

What does the level of inhibition of non competitive inhibitors depend on??

A

Number of inhibitor molecules present

58
Q

Effect of cyanide poisoning??

A

Affects the heart and intercostal muscles

No heart contraction or ventilation

59
Q

What is the effect of penicillin

A

Inhibits cell wall formation

60
Q

What is the effect of aspirin

A

Inhibits cyclooxygenase which affects vasoconstriction

61
Q

Examples of non competitive inhibitors

A

Aspirin and penicillin

62
Q

What is a cofactors??

A

A substance not made of amino acids

Required by an enzyme to function

Can be permanently bound to the enzyme or have a temporary part but help the esc to form

63
Q

What is a coenzyme??

A

A cofactor that is an organic molecule for an enzyme

Can donate or accept hydrogen ions or chemical groups

64
Q

What is a prosthetic group??

A

Permanent part of an enzyme, tightly bound

Contribute to the tertiary structure of the enzyme and vital to functioning

65
Q

What is an apoenzyme??

A

An inactive form of an enzyme

66
Q

What is an actifactor??

A

Something which binds to a apoenzyme and activates them

67
Q

How to calculate rate from a time graph

A

Find the gradient

Y/x

68
Q

How is a glycosidic bond broken in the digestion of a disaccharide??

A

Hydrolysis

69
Q

What is the sugar that forms from the digestion of a disaccharide

A

Beta glucose

70
Q

Why are different enzymes involved in each stage of the digestion process?

A

All enzymes are specific

Substrates are different shapes

Active site and substrate are complimentary so that the substrate will fit

71
Q

Which two factors should be controlled when investigating the effect of pH on the activity of an enzyme

A

Temperature

Concentration of substrate or enzyme

Biology (7 decks)

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