Unit 1. 4 - Enzymes

Question 1

what are enzymes?

Answer 1

biological catalysts that speed up the rate of metabolic reactions

Question 2

what is the lock and key hypothesis?

Answer 2

that there is an exact fit between the substrate and the active site of the enzyme

Question 3

what is anabolic enzymes?

Answer 3

enzymes that build larger products from smaller substrate molecules

Question 4

what are catabolic enzymes?

Answer 4

enzymes that break large substrate molecules into smaller products

Question 5

what is a lysozyme?

Answer 5

an enzyme found in tears and other secretions
function is to destroy pathogenic bacteria by breaking down their cell walls.

Question 6

what is the induced fit hypothesis?

Answer 6

when the substrate molecule changes the shape of the active site and the active site changes to fit the substrate molecule perfectly

Question 7

properties of enzymes?

Answer 7

specific - each will catalyse only 1 particular reaction
very efficient and will have a high turnover number - means they can convert many molecules of substrate into product per unit time

Question 8

what is activation energy?

Answer 8

the energy needed to break existing chemical bonds inside molecules

Question 9

why do enzymes lower the activation energy?

Answer 9

reduces the input of energy needed to allow reactions to take place ; which means they can take place at lower temps.

Question 10

what are the factors that affects enzyme activity?

Answer 10

temperature
ph
substrate concentration
enzyme contration

Question 11

what does increasing the temperature do?

Answer 11

increases the rate of reaction. This is because it gives molecules greater kinetic energy , increasing the chance of molecules colliding, leading to the formation of more successful enzyme - substrate complexes.

Question 12

why do enzymes denature at high temps?

Answer 12

vibrations break the hydrogen bonds within the active site of the enzyme, causing the shape of the active site of the enzyme to change.

Question 13

what happens when the enzyme concentration remains constant?

Answer 13

rate of reaction will increase as the substrate concentration increases. Reaction will level off once all the active sites are occupied ; number of available active sites become a limiting factor at higher substrate concentrations.

Question 14

what happens if the enzyme concentration increases?

Answer 14

there are more active sites available and therefore rate of reactions increases

Question 15

what is an enzyme inhibtor?

Answer 15

any substance which decreases the rate of an enzyme catalysed reaction or stops it.

can either be competitive or non competitive

Question 16

what are competitive inhibtors?

Answer 16

structurally similar to the substrate molecule- can fit into the active site instead of the substrate molecule
prevents enzyme substrate complexes forming

Question 17

what will increasing the substrate concentration do?

Answer 17

decrease the effect of the inhibtor as the enzyme = more likely to collide with a substrate molecule and form a successful enzymesubstrate complex

Question 18

what are non competitive inhibtors?

Answer 18

don’t bind to the active site ; but bind to any other part of the enzyme. alters the overall shape of the molecule , including the active site. substrate molecule can no longer fit into the active site. increasing the substrate concentration will not increase the rate of reaction in this case as the substrate can no longer fit into the enzyme’s active site. successful enzyme - substrate complexes can’t form.

Question 19

representing them on a graph?

Answer 19

only competitive inhibtion can be reduced by increasing the substrate concentration so mist be A

increasing substrate concentration won’t affect non competitive inhibtion so curve A

Question 20

What can enzymes be used for?

Answer 20

on a wide commercial scale in food , pharmaceutical and agrochemical industires

Question 21

why are enzymes immobilised?

Answer 21

enzyme can make direct contact with the substrate allowing the reaction to take place more quickly.

Question 22

immoblised enzymes advantages?

Answer 22

enzyme doesn’t contaminate the product
immobilised enzymes can be recovered and reused
only small quantity of enzyme = needed
enzymes have greater stability and denature at higher temps
immobilised enzymes can catalyse reactions over a wider range of PH
more than one enzyme can be used ; can be added and removed
greater control over process
can be used in a continous process

Question 23

what are biosensors?

Answer 23

detect biologically important molecules very rapidly even at low concentrations.

Question 24

how are they used?

Answer 24

to measure blood glucose concentration in individuals suffering from diabetes.