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enzymes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is the lock and key theory

A

enzymes have a specific shaped active site which is complementary to the shape of the substrate

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2
Q

what is the product in the lock and key model

A

an enzyme-substrate

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3
Q

does the active site change shape once the product is released

A

no

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4
Q

what is the induced fit model

A

the substrate collides with the active site and the active site changes shape to fit the substrate

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5
Q

what is the product of the induced fit model

A

an enzyme-substrate complex

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6
Q

why does the induced fit model have a low activation energy

A

the shape change in the enzyme places a strain on the substrate lowering the activation energy

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7
Q

what happens once the product is released in the induced fit theory

A

active site returns to original shape

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8
Q

what is activation energy

A

the extra energy that is required to enable a reaction to occur
eg heat

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9
Q

what are enzymes

A

biological catalysts that are able to lower the activation energy of a reaction to allow it to proceed quicker at lower temps so that molecules can be broken down to form new ones

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10
Q

what does starch break down into

A

maltose
enzyme- amylase

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11
Q

what does lipids break down into

A

fatty acids + glycerol
enzyme- lipase

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12
Q

what does protein break down into

A

amino acids
enzyme- protease

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13
Q

what does lactose break down into

A

glucose + galactose
enzyme- lactase

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14
Q

why is lysozyme antibacterial

A

it breaks down (hydrolysis) the polysaccharide (peptidoglycan) in bacteria cell walls, it does this by catalyzing the glyosidic bonds
the chains of modified beta glucose molecules are broken

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15
Q

what do reactions make up

A

the metabolism

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16
Q

what are the two types of reactions

A

catabolic and anabolic

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17
Q

what is a anabolic reaction

A

involve larger molecules being made by the condensation of smaller molecules

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18
Q

what is a catabolic reaction

A

involve the break down of larger molecules to smaller ones

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19
Q

how are enzymes made

A

protein synthesis

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20
Q

what are the two types of enzymes

A

intracellular- remain inside the cell
extracellular- secreted from cells to function

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21
Q

what is the turnover number

A

maximum number of substrate molecules it can convert to product molecules per until time

22
Q

what must be successful for enzymes reactions to happen

A

collisions between active site and substrate

23
Q

factors that effect enzymes

A

temp, pH, substrate conc., enzyme conc., presence of inhibitors

24
Q

ways to measure enzyme catalysis

A

time taken
rate of reaction
no. of conc of the product molecules formed

25
Q

how does temperature effect time taken

A
  1. mean time taken is high at low temps as kinetic energy is low so not many ESC formed
    2.time taken keeps decreasing as temp is increasing more ESC are formed
  2. once its reached optimum temp, theres a max turnover number of ESC
  3. as temp increases above optimum, the active site is changing shape (denatured) as hydrogen bonds are being broken due to increased kinetic energy
26
Q

how does temperature effect the rate of reaction

A
  1. rate is low as temp is low so theres less kinetic energy and less ESC produced
  2. rate is increasing exponentially because the temperature is increasing. ESC is increasing as more frequent successful collisions
  3. at optimal temperature so max turnover number of ESC is forming- increased kinetic energy
  4. denaturisation- rate is exponentially decreasing although the temp/kinetic energy are highest. active site is changing shape as site is changing shape as hydrogen bonds are breaking due to kinetic energy vibrations
27
Q

how does temp effect total mass of product produced over time

A

40 degrees- quicker rate of reaction due to higher temperature but will level due to denaturisation or no reactants left
30 degrees- rate of reaction is slower due to less kinetic energy so takes longer

28
Q

how does pH effect time taken for reaction to occur

A

A- at optimal pH so time taken for reaction to occur is lowest, ESC are forming at quickest
B- reaction will still be happening but not as much. small reversible changed in enzyme structure
C- highest mean time taken enzyme is not optimum as too acidic/alkaline. active site of enzyme is cahnging as ionic bonds breaking away from tertiary structure of protein. hydrogen bonds also affected

29
Q

what are 4 ways enzymes can be immobilized

A

physical absorption
covalent binding
entrapment
Membrane confinement

30
Q

what is an immobilized enzyme

A

an enzyme that is attached to an insoluble/inert material to prevent mixing with the product

31
Q

what is physical absorption

A

A weak physical force attaches the enzyme molecules to the surface of support particles. This is often caused by a combination of hydrophobic effects and salt links.

32
Q

what is covalent binding

A

The enzyme is retained on support surfaces by forming covalent bonds.

33
Q

what is entrapment

A

The enzyme is physically enclosed in a small space, such as within cross-linked polymers.

34
Q

what is membrane confinement

A

The enzyme molecules are confined within a semipermeable membrane

35
Q

what is the advantage to using immobilised enzymes over free enzymes

A

Immobilisation stabilises the enzyme molecules and they have a wider range of optimum pH and temperature. It is less affected by temperature and pH changes.

36
Q

why does immobilizing enzymes have this effect

A

By immobilising enzymes in an inert (non-reactive) substance this reduces the ability of the polypeptide chain to move and changes to temperature and pH have less of an effect on the 3D shape of the enzyme.

37
Q

what are the advantage of using immobilized enzymes in industry

A

The enzyme can be recovered and reused:
- this reduces costs
- it also means that only small amounts of an enzyme are needed
- the product is also not contaminated by the enzyme
- several enzymes can be used at once each acting on a specific substrate.
Lower/higher temperatures can be used and still have higher yields than using the free enzyme.

38
Q

example of using immobilized enzymes in industry

A

An industrial example is the use of immobilised lactase, which is used to produce lactose-free milk:
- the enzyme is immobilised in alginate gel beads
- milk is passed over the beads and the enzymes digest the lactose into glucose and galactose
- the milk is not contaminated by the enzyme and the beads can be used many times.

39
Q

why can immobilized enzymes be used as biosensors or analytical reagents.

A

enzymes are specific to a particular substrate

40
Q

why is the glucose oxidase electrode an example of a biosensor that is important for diabetics

A

it can detect glucose levels in the blood.

41
Q

how does the biosensor work

A
  • the enzyme glucose oxidase is immobilised in a gel
  • a small sample of blood is passed over the enzyme
  • when glucose in the blood comes into contact with the enzyme, a reaction occurs, which releases energy (chemical)
  • the energy released is converted into electrical impulses
  • the more energy released, the higher the concentration of glucose in the blood
  • a digital display of accurate concentration is available by referring to reference data stored in the processing unit.
42
Q

what is a biosensor

A

equipment that can detect a specific molecule

43
Q

how to produce industrial enzymes

A
  • Enzymes are produced by culturing microbes (bacteria and fungus)in fermentation vessels
  • The microbes produce enzymes as part of their normal metabolic activities.
  • microbes are then killed and the enzymes are extracted. And the culture is purified
  • enzymes added to substrate to catalyse reactions which would be difficult to carry out otherwise.
44
Q

Why enzymes are used in large scale industrial production

A
  • they are biological catalysts and speed up rate of reaction.
  • lower activation energies so reactions occur at lower temperatures saving energy and increasing efficiency.
  • Enzymes are specific, so there are few side reactions and so less waste products are formed which means fewer stages in the purification process.
45
Q

how do you immbolilize an enzyme

A
  • Substrates (e.g. maltose) are trickled through the vessel from the top
  • Reaction occurs as the substrate passes the immobilised enzymes
  • Products (e.g. glucose) are collected from the bottom
46
Q

disadvantages of immobilised enzymes

A
  • In adsorption the enzyme may become detached.
  • If enzymes are held within a substance (eg alginate bead) the substrate must diffuse into the gel which takes time.
  • Free enzymes can access the substrate immediately and reaction rates are therefore faster than using immobilised enzymes.
  • The presence of the alginate gel can alter the shape of the active site reducing activity compared with free enzyme.
  • Chemically bonding the enzyme is a complex process and is expensive.
  • Any contamination is costly because the whole system has to be shut down and the vessel re-sterilised.
47
Q

what is a competitive inhibitor

A

when it binds to the active site so the substrate can attach and form products

48
Q

is a competitive inhibitor reversible

A

yes, it can be removed

49
Q

is the concentration of competitive inhibitor is high what happens to the rate of reaction

A

decreases as active sites are less avaiable for substrates

50
Q

what is a non-competitive inhibitor

A

when it binds to the allosteric site and changes the shape of the active site/teriary structure so it cant bind to substrates

51
Q

is non-competitive inhibitor reversible

A

no, the enzyme is no longer functional

biology core components (8 decks)

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