Enzymes

Question 1

Enzymes

Answer 1

Biological catalysts made from proteins

Question 2

What are biological catalysts

Answer 2

They speed up chemical reactions by decreasing activation energy

Question 3

Lock and key hypothesis

Answer 3

Substrate fits enzyme active site perfectly

Question 3

Induced fit model

Answer 3

the proximity of the substrate leads to a change in the enzyme that forms the functional active site. This distorts the bonds in the substrate and lowers the activation energy

Question 4

No inhibitor

Answer 4

the substrate and enzyme fit together

Question 5

Competitive inhibitor

Answer 5

have a molecular shape similar to the substrate allowing them to occupy the active site of an enzyme

Question 6

Non- competitive inhibitor

Answer 6

attaches themselves to the enzyme at a binding site which changes the shape of the active site preventing enzyme substrate complex forming

Question 7

Allosteric site

Answer 7

Where the inhibitor changes the shape of the enzyme in a non-competitive inhibitor

Question 8

What make catalysts useful

Answer 8

They can be reused repeatedly and are therefore effective in small amounts

Question 9

activation energy

Answer 9

the minimum amount of energy required to activate the reaction

Question 10

how do enzymes work

Answer 10

They lower the activation energy which allows them the reaction to take place at a lower temperature

Question 11

What structure do enzymes have

Answer 11

They have a specific 3-D structure (tertiary) that is the result of their sequence of amino acids.

Question 12

What do a complimentary substrate and active site form

Answer 12

enzyme-substrate complex

Question 13

What must happen for enzymes to work

Answer 13

• Come into physical contact with its substrate
  -have an active site which fits the substrate

Question 14

how are enzyme-catalysed reactions measured

Answer 14

measuring its time course
- the formation of the products of the reaction
-the disappearance of the substrate

Question 15

What is the effect of temperature on enzyme action

Answer 15

A rise in temperature increase the kinetic energy of molecules which causes more collisions. More effective collisions means more enzyme substrate complexes. rate of reaction increases.

Question 16

How can temperature lead to the denaturation of an enzyme

Answer 16

causes the bonds in the enzyme to break resulting in the enzyme to change shape and the substrate fits less easily, slowing the rate of reaction. The enzyme becomes so disrupted that it stops working altogether (denatured)

Question 17

denaturation

Answer 17

permanent change to the active site causing the enzyme to stop functioning

Question 18

What is the effect of pH on enzyme action

Answer 18

each enzyme has a optimum pH if the pH is changed from the optimum it will reduce the rate of reaction.if the change in pH is beyond a certain pH the enzyme becomes denatured.

Question 19

how does pH affect the working of an enzyme

Answer 19

-A change in the pH alters the charge on the amino acids that make up the active site of the enzyme. Results in the substrate no longer being becoming attached to the active site- enzyme substrate complex can’t be formed
-depending on how significant the change in pH is, it may cause the bonds maintaining the enzymes tertiary structure to break and therefore the active site changes shape

Question 20

What is the effect of enzyme concentration on the rate of reaction

Answer 20

enzymes being catalysts in a reaction they are not used up and therefore work effectively at very low concentrations.As long as there is an excess of substrate an increase in the amount of enzyme leads to proportionate increase in the rate of reaction.

Question 21

what is the effect of substrate concentration on the rate of reaction

Answer 21

if the concentration of enzyme is fixed and substrate concentration is slowly increased, the rate of reaction increases in proportion to the concentration of substrate

Question 22

What are enzyme inhibitors

Answer 22

substances that directly or indirectly interfere with the functioning of the active site of an enzyme and so reduce its activity

Question 23

What reduces the effect of a competitive inhibitor

Answer 23

increased substrate concentration