Enzymes Flashcards
What is the function of enzymes?
Act as biological catalysts and speed up the rate of reaction by lowering the activation energy.
What are intracellular reactions?
Reactions that occur inside the cell.
What are extracellular reactions?
Reactions that occur outside the cell.
What is activation energy?
The minimum energy required for a chemical reaction to occur.
Describe the outdated lock and key model.
The active site is a fixed shape and cannot change.
It is complimentary to 1 substrate only.
When a successful collision occurs, an enzyme substrate complex forms.
Describe the new induced fit model.
Before the reaction, enzyme active site may not be fully complimentary to the substrate.
As the substrate binds, the active site distorts slightly to create a tighter fit to the substrate, forming the enzyme substrate complex.
This distorts the bonds in the substrate.
Which protein structure do enzymes have that makes them so specific?
Tertiary structure.
What is an enzyme substrate complex?
Forms when the active site binds to enzyme.
How does increasing enzyme concentration increase rate of reaction?
When would the enzyme be the limiting factor?
Why does rate of reaction plateau after a point? (limit/excess)
Increases rate of reaction as there are more active sites available, meaning more enzyme substrate complexes form.
Enzymes limit when the substrate is in excess.
The substrate limits when they are all in use, meaning there are spare active sites so rate of reaction plateaus.
How does increasing substrate concentration affect rate of reaction?
How does substrate concentration become the limiting factor?
Why does rate of reaction plateau after a point? (limiting/excess)
Rate of reaction increases.
Substrate concentration limits when not all available active sites are occupied.
Rate of reaction plateaus when all active sites are occupied, so substrates are in excess and active sites limit.
How does increasing temperature increase rate of reaction?
Increasing temperature increases the kinetic energy of particles, leading to more collisions and more successful enzyme/substrate complexes forming.
What happens to rate of reaction if temperature exceeds optimum?
Why?
If temperature exceeds optimum, rate of reaction falls as enzymes start to denature.
Fewer enzymes means fewer enzyme substrate complexes, leading to a slower rate of reaction as collisions are less likely to happen.
What happens to enzyme structure when they denature? (incorrect pH/too high temperature)
Enzymes lose the shape of their active site as the bonds in the tertiary structure start to break.
Give the number for rate of reaction when all enzymes have denatured.
Rate of reaction 0
How does pH affect rate of reaction?
If pH is above/below optimum, then rate of reaction decreases.
