ENZYMES

Question 1

Explain what catabolism is?

Answer 1

Breaking down reaction.

Question 2

Explain what anabolism is?

Answer 2

building up reaction.

Question 3

What are enzymes?

Answer 3

they are proteins that catalyse metabolic reactions.

Question 4

Expain how enzymes work? (enzyme action)

Answer 4

substrte fits into a active site on the enzyme, forming an enzyme substrate complex, bonds form between some of the amino acids of the enzyme, substrate turns to an enzyme product complex, products no longer fit in active site and are released.
Pg 31 textbook.

Question 5

Explain the lock and key model for enzymes?

Answer 5

enzyme active site is an exact match to the shape of the substrate (complimentary shapes).

Question 6

Explain the induced fit model?

Answer 6

The active site can mould itself around the substrste, the active site is therefore flexible, enzyme puts pressure on the substrate breaking bonds and lowering activation energy required for reaction to take place.

Question 7

Explain what co-factors are?

Answer 7

They are non-protein substances that enzymes requitre in order to function eg metal ions.

Question 8

Explain what prosthetic groups are?

Answer 8

Another type of co factor, haem is a prosthetic group in haemoglobin.

Question 9

Explain what co-enzymes are?

Answer 9

Coenzymes are a type of cofactor, non protein organic molecules, not permanently attached.

Question 10

What are some factors that affect enzyme activity?

Answer 10

Substrate and enzyme concentration.
Temperature.
pH.

Question 11

Explain how sustrate and enzyme concentration affects enzyme activity?

Answer 11

If the number of enzymes is kept at a fixed rate and the level of substrate is increased enzyme activity will also increase. (more substrates to fill available active sites).

Question 12

What does it mean when a rate of reaction graph levels off at the top?

Answer 12

Enzyme activity levels off as the number of substrate moecules becomes limiting.

Question 13

Explain how temperature affects enzyme activity?

Answer 13

Increasing temperature gives both substrate and enzyme more kinetice energy, increasing possibly collisions between enzyme and substrate.

Question 14

What are the negitive effects of heating up an enzyme?

Answer 14

if it gets over 60% the change is so great that he enzyme ceases to function and it has become denatured (permanent and irreversible change).

Question 15

Eplain how pH can affect enzyme activity?

Answer 15

Each enzyme has an optimum pH at either side of the optimum pH changes will reduce activity, pH disrupts the ionic bonds, eventually as the pH gets far enough away from the optimum denaturation occurs.

Question 16

What are the two types of enzyme inhibition?

Answer 16

competititve inhibition

non-competitive inhibition

Question 17

Expain competitive inhibition?

Answer 17

inhibitor substance competes with the usual substrate, these inhibitors are very smilar in shape to the normal substrate, if there is low quality of inhibitor substance then thare is little to no effect on enzyme, if high there is signifigant effect on thye enzyme.

Question 18

Explain non-compettive inhibition?

Answer 18

When an inhibitor attaches itself to a part of the enzyme other than active site, so active site is no longer complimentary to the substrate, in allosteric enzymes inhibitors bind at the allosteric site.

Question 19

What are the financial advantages of immobilistion?

Answer 19

production is continuous, product is enzyme free, enzyme can be reused, enzyme is supported and is more stable over range of temperature and pH.

Question 20

What are the methods of immobilisation?

Answer 20

Absorption, covalent bonding, cross linking, encapsulation and gel entrapment.

Question 21

Explain absorption as a form of immobilisation? (advantage and disadvantage)

Answer 21

enzymes are attached by weak forces to an inert substance eg glass or a matrix.
advantagte - easy and relatively cheap.
disadvantage - enzymes an be washed away, some active ites may be blocked.

Question 22

Explain covalent bonding? (advantage and disadvantage)

Answer 22

advantage - enzymes arnt washed away, resisitance to pH and tmepo.
disadvantage - expensive, active sites may be blocked.

Question 23

Explain cross linking as a form of immobilisation? (advantage and disadvantage)

Answer 23

Enzymes bonded covalently to a matrix eg cellulose, due to chemical reaction.
advantage - securely bound so not washed away.
disadvantage - active site blocked, distortion of active site.

Question 24

Explain encapsulation as a form of immobilisation? (advantages and disadvantages)

Answer 24

Enzymes are trapped inside a selectively permeable membrane eg nylon.
advantage - not bound, not blocked, activity unaffected.
disadvantge - substrate has to diffuse througyh mesh, may leak out.

Question 25

Explain gel entrampent as a form of immobilisation? (advantage and disadvantage)

Answer 25

Enzymes are trapped within polymers such as alginate beads.
advantage - cannot leak out acitve sites are not blocked.
disadvantage - resisitance to the substrate diffusing into gel matrix.