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Biology > 4 - Enzymes > Flashcards

4 - Enzymes Flashcards

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1
Q

Define co-enzyme

A

A cofactor that is an organic molecule

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2
Q

Define catabolic

A

Reactions that break down large molecules into small ones

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3
Q

What 4 factors affect the rate of enzyme-controlled reactions?

A
  • temperature
  • pH
  • enzyme conc
  • substrate conc
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4
Q

Explain how denaturing leads to a loss of enzyme function

A
  • bonds holding the secondary and tertiary structure together are broken
  • changes the precise shape of the enzyme and active site
  • substrate no longer complimentary
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5
Q

Describe how the induced fit model works

A
  • substrate not initially complimentary to active site
  • active site is flexible
  • molds itself around substrate
  • returns to original shape after
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6
Q

What is an enzyme’s temperature coefficient?

A

Q10
How much the rate of reaction increases for a 10-degree rise in temperature
Usually around 2

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7
Q

Define anabolic

A

Reactions that build large molecules from small monomers

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8
Q

How are prosthetic groups a part of enzymes? Give an example

A

Bound permanently and are part of its structure

eg. Zn2+ part of carbonic anhydrase in RBCs

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9
Q

How do coenzymes work? Give an example.

A

Bind temporarily to enzyme, transfer chemical groups in substrate
eg. vitamins

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10
Q

How do ions act as cofactors for enzymes?Give an example.

A

Bind to allosteric site and ensure active site is the right shape
Cl- ions for amylase

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11
Q

Explain how pH can affect the 3d structure of an enzyme

A

high conc of H+ ions interact with the charged/polar R groups and distorts the 3d shape

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12
Q

Define cofactor

A

A non-protein molecule that is required for a molecule to function (by binding to allosteric site)

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13
Q

Name an intracellular enzyme and its function

A

catalase

breaks down hydrogen peroxide into water and oxygen

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14
Q

Give an example of an extracellular enzyme

A

Any digestive enzyme eg. salivary amylase, pepsin, maltase…

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15
Q

Define intracellular with regards to enzymes

A

An enzyme that catalyses a reaction within the cell it is produced in

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16
Q

Define extracellular with regards to enzymes

A

An enzyme that catalyses a reaction outside of the cell it is produced in

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17
Q

Define substrate

A

A specific molecule which interacts with an enzyme, fits into the active site

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18
Q

Define activation energy

A

The energy that needs to be supplied for a chemical reaction to start

19
Q

Define active site

A

A specific region of an enzyme that is complementary to the substrate molecule

20
Q

How do enzymes affect a reaction in terms of energy

A

They lower the activation energy therefore less energy has to be supplied to start the reaction

21
Q

What is Vmax

A

The maximum rate at which the enzyme catalyses a reaction

22
Q

Explain how increasing the temperature increase the rate of an enzyme controlled reaction?

A

As temp increases KE of enzyme and substrate increases
collide more frequently
more frequent successful collisions
more E-S complexes formed

23
Q

Explain how low temperatures affect the rate of an enzyme controlled reaction?

A

As temp decreases KE of enzyme and substrate decreases
collide less frequently
less frequent successful collisions
fewer E-S complexes formed

24
Q

Explain how very high temperatures affect the rate of an enzyme controlled reaction?

A
  • High temperatures can put strain on the bonds holding the enzyme together as there is more kinetic energy moving them around etc.
  • Bonds can distort and break
  • substrate no longer complementary to active site
  • enzyme not functional
25
Q

How do extreme pHs affect the rate of an enzyme controlled reaction?

A

At extreme pHs, high conc. of H+ and OH- ions disrupt and break bonds between amino acids
Substrate no longer complementary to active site
-enzyme not functional

26
Q

Describe the lock and key model

A

Enzyme complementary to active site of enzyme

fit together and temporary bonds form, forming an E-S complex

27
Q

State any assumptions the lock and key model makes

A
  • enzyme is rigid and doesn’t change at all

- substrate is perfectly complementary to shape of active site

28
Q

Describe how the induced fit model is different from the lock and key model

A

Substrate not initially complementary to the active site
Active site flexible
Moulds itself to the substrate
Distorts the bonds in the substrate, lowering activation energy
Returns to original shape after

29
Q

What would this graph look like:

rate of reaction as substrate conc. changes?

A

Rate of reaction increases as substrate conc. increases and then plateaus as all active sites are saturated

30
Q

What would this graph look like:

rate of reaction as enzyme conc. changes?

A

Rate of reaction increases as enzyme conc. increases and then plateaus as other limiting factors eg. substrate conc.

31
Q

What could your dependent variables be in an experiment to measure the rate of a reaction?

A

How quickly substrate used up

How quickly product formed

32
Q

How do competitive inhibitors work?

A

Similar shape to substrate

binds to active site so substrate can’t

33
Q

How do competitive inhibitors affect the rate of reaction and why does this happen?

A

Rate of reaction for given substrate conc. decreases however the Vmax is still reached because there will eventually be considerably more substrate than inhibitor so it will not effect it

34
Q

Name 2 examples of competitive inhibitors and their roles

A

Statins- inhibit cholesterol production

Asprin - inhibit chemicals responsible for pains and fevers

35
Q

How do non-competitive inhibitors work?

A

Complimentary to allosteric site, creates a conformational change to the shape o the active site
Substrate can’t bind

36
Q

How do non-competitive inhibitors affect the rate of reaction and why does this happen?

A

Increasing substrate conc. will not overcome the inhibition, the graph would be lower (ROR slower) and plateaus beneath normal graph

37
Q

How do end product inhibitors work?

A

-end product acts as a negative feedback by inhibiting a previous step in its production, this prevents an accumulation of certain substances

38
Q

Enzymes that are not yet active are called

A

Apoenzymes

39
Q

Define apoenzyme

A

An enzyme that is not yet active

40
Q

Enzymes that have been activiated with the addition of a cofactor are called

A

Holoenzymes

41
Q

Define holoenzymes

A

Enzymes that have been activiated with the addition of a cofactor

42
Q

Why could precursor activation be necessary for enzymes?

A

The active enzyme could cause damage in one area so is only activated when it gets to its site

43
Q

Give an example of a precursor enzyme and why it is necessary for it to be activated somewhere else

A

Pepsin (hydrolyses proteins into amino acids)

could be dangerous in cells so it in secreted inactively

44
Q

Describe 2 ways cofactors are necessary for enzymes function

A

cofactors transfer groups between reactants

form part of the active site

Biology (17 decks)

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