2.5 - Enzymes

Question 1

How are enzymes used in the production of lactose free milk?

Answer 1

• Lactose is a disaccharide and can not be absorbed by the gut
• Many adults are intolerant of the lactose in milk, as we get older the gene that produces lactase switches off
• lactose gets fermented by bacteria in the large intestine resulting in nausea, abdominal pain, and dioreahha
• milk is treated with lactase which breaks lactose into monosaccharides glucose and galactose which are easily absorbed by the gut
• lactase is obtained from the fungus kluyveromyces lactic

Question 2

Uses of lactose free milk

Answer 2

• increase sweetness of milk, (glucose and galactose)
• reduces crystallisation of ice creams
• shortens the production time for yoghurt or cheese

Question 3

Common uses of enzymes in industry

Answer 3

• detergents contain proteases and lipases to help breakdown protein and fat stains
• enzymes are used to break down the starch in grains into biofuels that can be combusted
• in the textile industry enzymes help in the processing of fibers, eg polishing cloth to make it look shinier
• in the brewing industry enzymes help a number of processes including the clarification of beer.
• paper production uses enzymes to help in the pulping of wood.

Question 4

How can enzymes be immobilized

Answer 4

• aggregations of enzymes bonded together
• attached to surfaces liek glass
• entrapped in gels, eg algenate gel beads

Question 5

What is an enzyme

Answer 5

A globular protien that increases the rate of a biochemical reaction by lowering the activation energy threshold. (i.e a biological catalyst)

Question 6

What do enzymes do

Answer 6

• lower the activation energy of a reaction by stressing the bonds in a substrate,

Question 7

define active site

Answer 7

region on the surface of an enzyme to which substrates bind and which catalyses the reaction

Question 8

Examples of enzymes

Answer 8

pepsin: found in stomach and digests proteins
amalyse: breaks down starch

Question 9

explain how the enzyme substrates complex attracts eachother

Answer 9

polar regions of amino acids attract substrate and active site of the enzyme

Question 10

what do substrates do to an enzyme

Answer 10

induce a conformational change to the active site

Question 11

collision

Answer 11

coming together of substrate molecule and active site

Question 12

most enzyme reaction occur when-

Answer 12

substrates are dissolved in water

-all molecules in water are in random motion

Question 13

what is denaturation

Answer 13

changing the structure of a protein (enzyme) so that it can not carry out its function
irreversibly alters the 3d structure of the active site

Question 14

what causes denaturation

Answer 14

High temperatures cause denaturation as the extra energy leads to increased vibration, breaking intra-molecular bonds.
Changes in Ph cause denaturation as hydrogen bonds between amino acids in the structure of the enzyme are broken

Question 15

how do low temperatures affect reactions

Answer 15

low temperatures result in insufficient thermal energy for the activation of a given enzyme-catalysed reaction to be achieved.

Question 16

how will increasing temp below optimal temp affect rate of reaction

Answer 16

increasing the temperature will increase the speed and motion of both enzyme and substrate resulting in higher enzyme activity. This is because a higher kinetic energy will result in more frequent collisions between enzyme and substrate.

Question 17

outline the effect of substrate concentration of enzyme activity

Answer 17

• increasing substrate concentration increases the rate of reaction
• at the optimum concentration of substrate molecules all active sites are full and working at maximum efficiency. Any concentration more than optimum will have no added affect.

Question 18

Advantages of enzyme immobilization

Answer 18

C - concentration of substrate can be increased since the enzyme is not dissolved (increased rate of reaction)
R - Recycled enzymes can be used many times
S - Seperation of products is straightforward
S - stability of enzyme in temprature and pH is inreased, reducing rate of degradation