1.7 Enzyme action

Question 1

What is an active site

Answer 1

A small part of an enzyme that attaches to a substrate to catalyse a reaction
It is specific and unique in shape due to the specific folding and bonding in ther tertiary structure of the protein

Question 2

How do enzymes act as biological catalysts

Answer 2

Each enzyme lowers the activation energy of a reaction to peed up the reaction without getting used up

Question 3

What does the Lock and Key model suggest (4)

Answer 3

• The active site is a fixed shape and due to random collisions the substrate can collide and attach to the enzyme
• forming an ENZYME SUBSTRATE COMPLEX
• Once they are in the ENZYME SUBSTRATE COMPLEX it will cause the substrate to slightly distort in shape lowering the activation energy
• After the substrate distorts in shape the products are then released and the active site is empty and ready to be reused

Question 4

What is the analogy used for in the induced fit

Answer 4

The enzyme is a glove and the substrate is your hand

Question 5

Explain the glove and hand analogy of the inducing fit

Answer 5

A glove is not exactly complimentary to your hand but when your hand enters it enables the glove to mold around your hand to become completely complimentary

Question 6

Describe the induced fit model of enzyme action (4)

Answer 6

• Substrate binds to (not completely complimentary) active site of enzyme
• The enzymes active site is induced, or slightly changes shape, so it is complimentary to substrate
• Forming an enzyme Substrate complex
• Causing bonds in substrate to distort lowering the activation energy

Question 7

Why are enzymes effective in small quantities

Answer 7

They can be reused repeatedly

Question 8

What are the conditions required for a reaction (between enzyme and the substrate) (3)

Answer 8

• Reactants (substrate) must collide with sufficient energy to alter the arrangements of their atoms to form the product
• The free energy of the products must be less than that of the reactants
• The activation energy must be reached

Free energy= The energy available in a system to do work

Question 9

Define activation energy

Answer 9

The minimum amount of energy required for a reaction to take place

Question 10

Enzymes lower the activation energy

Answer 10

Allows reactions to take place at a lower temperature than normal
This enables some metabollic processes to occur rapidly at 37*c

Question 11

If enzymes didn exist what problem would arise

Answer 11

Metabollic processes would proceed to slowly to sustain life

Question 12

What is the active site made out of

Answer 12

Amino acids

Question 13

What holds the active site together

Answer 13

Bonds- Ionic hydrogen

Question 14

What happens if you change certain amino acids that are not a part of the active site

Answer 14

It prevents the enzyme from functioning as the changed amino acid could be the one that forms hydrogen bonds leading to a change in the tertiary structure

Question 15

Describe how models of enzyme action have changed overtime

Answer 15

Initially lock and key model where it stated that the active site was a fixed shape and complementary to one substarte
Now it is induced fit model

Question 16

Explain the specificity of enzymes

Answer 16

Specific tertiary structure determins shape of active site -the tertiary struc is dependent on the sequence of amino acids(primary structure)
Active site is complementary to a specific substrate
Only this substrate can bind to the active site,including induced fit forming an enzyme substrate complex