Enzymes

Question 1

How can you measure the course of enzyme catalyzed reactions?

Answer 1

Measuring time taken for reaction to occur, measuring rate of reaction, measuring concentration of product

Question 2

How can you impact the RoR of a catalyised reaction?

Answer 2

pH, temp, concentration of enzymes or substrate, presence of inhibitors

Question 3

At optimum temperature?

Answer 3

Ek increases, more successful collisions between enzyme and substrate, more E-S complexes formed

Question 4

pH at optimum?

Answer 4

Charge of active site is complementary to charge of substrate, more successful collisions, more ES complexes

Question 5

Minor pH change?

Answer 5

Small reversible change to enzyme structure, H/OH ions cause charge of active site to repel substrate

Question 6

Extreme pH changes?

Answer 6

H/OH ions interfere with ionic bonds (excess H or OH are attracted to their complementary charges in R groups neutralising them.) Ionic bonds break (and hydrogen), unravel tertiary structure

Question 7

how does a competitive inhibitor reduction the rate of reaction?

Answer 7

The inhibitor competes with the substrate to bind to the active site

Question 8

where do non competitive inhibitors bind?

Answer 8

allosteric sites

Question 9

what is cyanide an inhibitor for?

Answer 9

cytochrome oxidase, found in the inner mitochondrial membrane, stops the sequence of reactions that produces ATP

Question 10

Cofactor?

Answer 10

Non-protein chemical that helps/ is necessary for a biological chemical reaction

Question 11

Types of cofactor?

Answer 11

Cofactor: relatively small chemical, normally inorganic
Coenzyme: Large organic molecule
Prosthetic group: permanent part of the enzyme structure

Question 12

example of cofactor?

Answer 12

NAD, large organic molecule which temporarily binds to respiration enzymes. Transfer H atoms from one molecule to the next

Question 13

what is meant by enzymes being specific?

Answer 13

any individual enzyme can only catalyse one reaction, only one substrate can fit

Question 14

more advantages of immobilised enzymes?

Answer 14

high temp would denatured other unwanted enzymes/ kill contaminating microorganisms
Can make more product/ make product faster at higher temperature.
Enzymes can be easily added or removed to control RoR
Can be reused
Dont contaminate product

Question 15

Disadvantages of immobilised enzymes?

Answer 15

substrate needs to diffuse through gel/membrane
smaller SA of enzyme
Enzyme is at a lower concentration when immobilised
immobilised have low Ek
Immobilization can affect active site so fewer E-S complexes

Question 16

Immobilised enzymes?

Answer 16

Enzymes fixed to an inert matrix/ insoluble agent through which the substrate flows/diffuses

Question 17

uses of immobilization?

Answer 17

measuring blood sugar in diabetics, producing lactose free milk, in biosensors

Question 18

bio sensor?

Answer 18

instrument that measures a SPECIFIC metabolite in a mixture of molecules by converting energy into an electrical signal

Question 19

what are the pros of using biosensors?

Answer 19

They give quantitative data, and they can detect very small concentrations of molecules:sensitive, they can detect a single type of molecule in a mixture: specific

Question 20

methods of immobilising enzymes?

Answer 20

Fix in gel beads/ membrane or cellulose fibres

Question 21

is non competitive inhibition permanent?

Answer 21

many are permanent but those involved in control of metabolic pathways are reversible

Question 22

example of competitive inhibition

Answer 22

malonic acid inhibits succinate which breaks down succinc acid into fumaric acid

Question 23

metabolism?

Answer 23

summer of all of an organisms chemical processes, comprising anabolic and metabolic pathways

Question 24

Metabolic pathway?

Answer 24

A sequence of enzyme controlled reactions in which a product of one reaction is a reactant in the next

Question 25

Inactivation?

Answer 25

A small reversible reduction in enzyme activity e.g at low temperatures or slightly varied pH

Question 26

Example of enzyme with highest turn over number?

Answer 26

Catalase: breaks down toxic waste, hydrogen peroxide

Question 27

higher RoR wit immobilised enzymes in beads?

Answer 27

Use smaller beads= larger surface area= substrate has easier access to enzyme molecule

Question 28

Effect of temperature on a free enzyme compared to immobilised?

Answer 28

IE has a greater range of optimum, IE denatured at a greater temperature, IE has a higher RoR at lower temperatures