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Biology Year 1 > 2.4 enzymes > Flashcards

2.4 enzymes Flashcards

1
Q

what are enzymes

A

Are globular Proteins that act like biological catalyst.

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2
Q

what is an active site

A

which is an intended area on the surface of an enzyme molecule with a shape that is complementary to the shape of substrate molecule.

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3
Q

how is the shape of active site determined by

A

The shape of A.S is specific due to specific folding in tertiary structure.

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4
Q

why are they seen as catalyst

A

They speed up the rate of a reaction and remains uncharged + reusable.

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5
Q

what us turnover number

A

Turnover number is the number of reactions that an enzyme can catalyst this per second.

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6
Q

intracellular

A

inside the cell

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7
Q

1 example of intracellular enzyme and what is does

A

catalase, is found inside liver cells that breakdown hydrogen peroxide into O2 + H2O

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8
Q

extracellular

A

outside the cell

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9
Q

2 examples of extracellular enzymes and what is does

A

Trypsin Is made in pancrease and acts in lumen of small intestine to digest protein.

Amylase is made in salivary glands and digest polysaccharides into disenchants in the mouth.

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10
Q

what is a cofactor

A

a substance that must be present to ensure that an enzyme catalysed reaction takes place at appropiate rates

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11
Q

what is a prosthetic group

A

a cofactor that’s permenantly bound by covalent bond to an enzyme molecule

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12
Q

what are mineral ion cofactors & coenzymes

A

cofactors that form temporary associations

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13
Q

examples of co-enzymes

A

1) NAD: used in respiration
2) NADP: used in photosynthesis

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14
Q

what is an anabolic reaction

A

reaction that builds smaller molecules into larger ones and are catalysed by enzymes

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15
Q

example of anabolic

A

different cell componenets are synthesised + assembled into cells which then form tissues then organs then whole organisms

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16
Q

what is catabolic reactions

A

chemical reactions that break big molecules into smaller ones and are catalysed by ezymes

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17
Q

example of catanolic reaction

A

in digestion

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18
Q

what is Vmax

A

max initial velocity / rate of enzyme catalysed reactions

19
Q

what is activation energy

A

they energy that needs to be supplied for reaction to start

20
Q

what A.E is too high what 2 mechanisms help to lower it

A

Induced Fit Hypothesis
Lock & Key Hypothesis

21
Q

what happens in Lock & Key

A
  • The substrate fits into A.S
  • The substrate is held in a way where the R groups within the A.S can interact with the substrate forming temporary bonds
  • This puts strain on substrate bonds which help the reaction
22
Q

what happens in Induced Fit

A
  • When the substrate fits into the enzyme it changes shape.
  • The initial interactions between enzyme + substrate is relatively weak but these weak interactions rapidly induce change in enzymes tertiary structure that strengthens binding to put strain on substrate molecule to weaken a particular bonds in substrate to reduce A.E
23
Q

Enzyme - substrate complex

A

When substrate in bonded to the A.S

24
Q

Enzyme - product complex

A

The products formed when substrates then react

25
Q

what 3 things happens when a substance is heated

A
  1. The KE causes the molecule to move faster
  2. This increases the rate of collisions
  3. This increases the force they collide
26
Q

what happens is both substrate and enzyme is heated

A

They will both move faster which will increase the number of successful collisions. This then increases the rate of formation of ESC nad increase rate of EPC.

27
Q

what happens when the temperature is too high

A

when an enzyme is heated it vibrates which may break bond i.e hydrogen or ionic which changes the tertiary structure and A.S to not allow substrates to fit in which lower ROR. If more heat is applied then enzyme is denatured and no longer complementary

28
Q

ROR equation

A

1/ Time taken to reach end point

29
Q

what is Q10

A

refers to the temperature coeffiecient and the increase is ROR when temperature is increased by 10 degrees

30
Q

Q10 equation

A

ROR at ( T + 10 degrees ) / ROR at ( T )

31
Q

what is buffer

A

something that can resist change in pH

32
Q

how does pH affect ROR

A
  • A hydrogen ions has a positive charge and is attracted to negative regions
  • excess hydrogen ions interfere with h-bonds and ionic bond in enzyme and alter shape of A.S
  • This happens due to H-ions cluster around negatively charged sections of R group
  • This doesn’t allow substrate to fit in which lowers ROR
33
Q

what happens when there is low concentration of substrate

A

If there is a low conc of substance, the ROR is lower as there will be fewer collisions between enzymes + substrate.

34
Q

what happens when there is high conc of substrate

A

high conc of substrate will increase ROR as there will be more succesful collisions. This then leads to an increase in ES complex

35
Q

what happens if there is too high of a concentration of substrates

A

it wont affect the rate of reaction as all the enzymes are being used up. if there is more substrate added, they cant sucessfully collide with enzymes as active site is being used. Thiss causes a plateau.

36
Q

how does high enzyme concentration affect ROR?

A

increases number of enzyme molecule avialable and thus increasing number of active sites, which leads to higher sucessfull collision with substrates and increases rate of ESC.

37
Q

what happens when enzymes concentration is too high?

A

the rate of reaction plateaus as all active sites have been used.

38
Q

what is an inhibitor

A

a substance that reduces or stops a reaction.

39
Q

state two ways inhibitor stops reaction

A
  1. they could do this by combining with enzymes in a way that influences how substrate binds to enzymes or affects the enzymes turnover number.
  2. some may block the active site is no longer complementany due to the A.S shape changing.
40
Q

what is completetive inhibitor?

A

Inhibitation of an enzymes, where the inhibitor molecule has a similar shape to that of the substrates molecule and competes with substrates for the A.S it blocks the A.S ro prevent ES formation.

41
Q

how does it work?

A

A molecular or part of a molecular that has similar shape to the substrate can fit into the A.S.
This blocks the susbtrate from entering and prevents catalysis
This forms an enzyme inhibitor complex.
The enzyme can’t function (catalyse the reaction)and is inhibitated.
The inhibitor molecule isn’t changed by the enzyme molecule.
Substrate + inhibitor compete to bind to A.S.
this reduces the rate of formation of ES complex.
Most are reversible (temporanly binded + if very high enough substrate is added it can get knocked off.

42
Q

how does competitive inhibitor affect ROR

A

The degree of inhibitor depends relative conc of substance, inhibitor and enzyme molecule.
Increase inhibitor = decrease ROR
increase sub conc = increase ROR
A competitive inhibitor decrease ROR bur doesn’t change Vmax.

43
Q

how does non-competitive inhibitor affect ROR and definition

A

Inhibition of an enzyme where the completitor molecule attches to part of enzyme (allosteric site) which changes shape of A.S which prevents ES complex from forming as the A.S shape is no longer complementory to substrate.
This binding causes tertiary structure to change.

The maxuim ROR is reduced
Increased inhibitor= decrease ROR as A.S is unavailable.
Increase sub conc = doesn’t overcone effect of NIC

44
Q

what is end product inhibition

A

Type of enzyme inhibition where the product of a reaction acts as an inhibitor to the enzymes that produces it

Biology Year 1 (16 decks)

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