1-4 Enzymes Flashcards
Why does a protein hormone only affect certain cells?
A protein hormone has an active site with a specific 3-dimensional shape that is complementary to the cell membrane receptor.
Cells without the complementary receptor are unaffected as the hormone cannot bind.
What are the three main factors that affect enzyme activity?
- Temperature
- pH
- Presence of Inhibitors
What happens to enzyme activity at lower temperatures?
Molecules move slower, resulting in fewer collisions between enzyme and substrate, reducing the rate of enzyme-catalysed reactions.
What occurs to enzyme activity as temperature increases?
Enzyme activity increases until the temperature is high enough to denature the enzyme, changing its shape and function.
What is meant by ‘denatured’ in the context of enzymes?
An enzyme that has ceased to function due to the destruction of chemical bonds in the active site.
What is the optimum pH for an enzyme?
The pH at which the enzyme works best.
How can a change in pH affect enzyme activity?
It can alter the charge on amino acids in the protein, affecting the affinity of the active site for the substrate.
What are enzyme inhibitors?
Chemicals that bind to enzymes and decrease their activity.
What are the two types of enzyme inhibitors?
- Competitive inhibitors
- Non-competitive inhibitors
How do competitive inhibitors affect enzyme activity?
They have a complementary shape to the active site and bind to it, preventing substrate binding.
Describe how non-competitive inhibitors function.
They bind to another part of the enzyme, causing a change in the shape of the active site, preventing effective substrate binding.
What is the general relationship between substrate concentration and reaction rate?
As the concentration of substrate increases, the rate of reaction increases until the enzyme becomes saturated.
How does enzyme concentration affect the rate of reaction?
As the concentration of the enzyme increases, the rate of reaction also increases due to more active sites being available.
