1.7 Enzyme action Flashcards
What are enzymes
Globular proteins that have a tertiary structure
They catalyse reactions without being used up
What is an active site
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
What effect does an enzyme have on the rate of reaction
It lowers the activation energy therefore speeding up the reaction
What are the two models in which enzyme action is represented
Lock and key
Induced fit
What does the ‘Lock’ and the ‘Key’ symbolise
Lock= enzyme
Key= substrate
They fit together due to their complimentary shape
What does the Lock and Key model suggest (4)
- 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
What is the analogy used for in the induced fit
The enzyme is a glove and the substrate is your hand
Explain the glove and hand analogy of the inducing fit
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
What does the induced fit model suggest about enzyme action (3)
- The enzymes active site is induced, or slightly changes shape, to mould around the substrate
- When the enzyme substrate occurs due to the enzyme moulding around substrate it puts strain on the bonds and therefore lowers the activation energy
- The products are then removed and the enzymes active site returns to its orginal shape
Why are enzymes effective in small quantities
They can be reused repeatedly
What are the conditions required for a reaction (between enzyme and the substrate) (3)
- 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
Define activation energy
The minimum amount of energy required for a reaction to take place
Enzymes lower the activation energy
Allows reactions to take place at a lower temperature than normal
This enables some metabollic processes to occur rapidly at 37*c
If enzymes didn exist what problem would arise
Metabollic processes would proceed to slowly to sustain life
What is the active site made out of
Amino acids
