Enzymes Flashcards
lock and key hypothesis means
The substrate fits perfects into the enzyme active site
theory of induced fit means
The shape of the active site changes to fit more perfectly around the substrate, putting pressure on the bonds in the substrate to lower the activation energy
Enzymes working inside the cell are called… and outside the cell are called …
Enzymes working inside the cell are called intracellular and outside the cell are called extracellular
The active site and substrate are not the same shape, they are:
Complementary
Enzymes only catalyse one substrate, so they are described as
Specific
The rate of an enzyme catalysed reaction increases with increasing temperature due to…
Increased kinetic energy causing increased frequency of successful collisions
When the temperature is too high enzymes will…
Denature, meaning the hydrogen bonds break and the shape of the active site is lost
Enzyme controlled reactions will be fastest at a temperature and pH described as the
Optimum
The four factors that can limit the rate of an enzyme controlled reaction are
Temperature, pH, enzyme concentration, substrate concentration
What does a buffer do?
Maintain a constant pH
What happens when pH is only slightly above or below the optimum
Small changes in pH cause small reversible changes in enzyme structure, causing inactivation.
What is inhibition?
Inhibition is when enzyme action is slowed down or stopped by another substance
What is a competitive inhibitor?
A competitive inhibitor is structurally similar to the substrate and binds to the enzyme active site, blocking it.
What is a non competitive inhibitor
Non-competitive inhibition involves an inhibitor binding away from the active site, altering the active site’s shape
What effect will increasing substrate concentration have when either a competitive or non competitive inhibitor is present?
Competitive if the substrate concentration is increased so will the rate of reaction. Non competitive the rate of reaction is unaffected by substrate concentration.
