Enzymes (A) Flashcards
What are enzymes?
Biological catalysts regulating biological processes in living organisms
What do enzymes catalyse?
A wide range of intracellular and extracellular reactions
What type of proteins are enzymes?
Globular proteins
What is the function of enzymes?
To lower the activation energy
What is the activation energy?
The activation energy is the energy required for chemical reactions to take place
How do enzymes lower the activation energy?
Through the formation of enzyme-substrate complexes
What happens to the rate of reaction when the activation energy is lowered?
The rate of reaction is increased
Are enzymes specific?
Yes, enzymes are specific to their substrates
What determines the enzyme specificity?
The enzyme’s unique tertiary structure shapes the active site to fit specific substrates
What is the ‘lock and key method’?
When only molecules complementary in shape to the active site will bind to it to form an enzyme-substrate complex, the shape of active site is fixed or rigid
What are the issues with the ‘lock and key method’ hypothesis?
The belief of a rigid structure is an issue because the enzyme’s shape is not rigid but flexible
What is the ‘Induced-fit model’?
The active site of an enzyme is flexible and can change its shape slightly. The substrate interacts with the active site causing it to change shape. As the enzyme changes shape a strain is placed on bonds within the substrate molecule, thus lowering the activation energy.
During hydrolysis what happens to an enzyme?
A strain is placed on the substrate molecule, this distorts a particular bond and so lowers the activation energy needed to break the bond
During a condensation reaction what happens to an enzyme?
Pulls the molecules closer together, making them more likely to react, helping to form a new bond between them, and releasing a water molecule in the process
