2.4 enzymes

Question 1

what are enzymes

Answer 1

Are globular Proteins that act like biological catalyst.

Question 2

what is an active site

Answer 2

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

Question 3

how is the shape of active site determined by

Answer 3

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

Question 4

why are they seen as catalyst

Answer 4

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

Question 5

what us turnover number

Answer 5

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

Question 6

intracellular

Answer 6

inside the cell

Question 7

1 example of intracellular enzyme and what is does

Answer 7

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

Question 8

extracellular

Answer 8

outside the cell

Question 9

2 examples of extracellular enzymes and what is does

Answer 9

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.

Question 10

what is a cofactor

Answer 10

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

Question 11

what is a prosthetic group

Answer 11

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

Question 12

what are mineral ion cofactors & coenzymes

Answer 12

cofactors that form temporary associations

Question 13

examples of co-enzymes

Answer 13

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

Question 14

what is an anabolic reaction

Answer 14

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

Question 15

example of anabolic

Answer 15

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

Question 16

what is catabolic reactions

Answer 16

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

Question 17

example of catanolic reaction

Answer 17

in digestion

Question 18

what is Vmax

Answer 18

max initial velocity / rate of enzyme catalysed reactions

Question 19

what is activation energy

Answer 19

they energy that needs to be supplied for reaction to start

Question 20

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

Answer 20

Induced Fit Hypothesis
Lock & Key Hypothesis

Question 21

what happens in Lock & Key

Answer 21

• 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

Question 22

what happens in Induced Fit

Answer 22

• 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

Question 23

Enzyme - substrate complex

Answer 23

When substrate in bonded to the A.S

Question 24

Enzyme - product complex

Answer 24

The products formed when substrates then react

Question 25

what 3 things happens when a substance is heated

Answer 25

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

Question 26

what happens is both substrate and enzyme is heated

Answer 26

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.

Question 27

what happens when the temperature is too high

Answer 27

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

Question 28

ROR equation

Answer 28

1/ Time taken to reach end point

Question 29

what is Q10

Answer 29

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

Question 30

Q10 equation

Answer 30

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

Question 31

what is buffer

Answer 31

something that can resist change in pH

Question 32

how does pH affect ROR

Answer 32

- 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

Question 33

what happens when there is low concentration of substrate

Answer 33

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

Question 34

what happens when there is high conc of substrate

Answer 34

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

Question 35

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

Answer 35

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.

Question 36

how does high enzyme concentration affect ROR?

Answer 36

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.

Question 37

what happens when enzymes concentration is too high?

Answer 37

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

Question 38

what is an inhibitor

Answer 38

a substance that reduces or stops a reaction.

Question 39

state two ways inhibitor stops reaction

Answer 39

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.

Question 40

what is completetive inhibitor?

Answer 40

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.

Question 41

how does it work?

Answer 41

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.

Question 42

how does competitive inhibitor affect ROR

Answer 42

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.

Question 43

how does non-competitive inhibitor affect ROR and definition

Answer 43

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

Question 44

what is end product inhibition

Answer 44

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