Enzymes Flashcards
What are enzymes ( definition).
Enzymes are proteins with a complex 3D globular structure.
What is denaturation and what does it cause.
All of the tertiary and quaternary structures bonds break and then form alternative bonds elsewhere. This changes the active site of the enzyme so the substrate cannot fit in the enzyme.
This shape change is permanent.
What is an active site (definition).
Is a specific shape and chemical environment where a chemical reaction can occur.
What are cofactors?
An additional non-protein molecule that is needed by some enzymes to help reactions.
Tightly bound cofactors are called prosthetic groups.
What are tightly bounds cofactors called ?
Prosthetic groups.
What is another name for cofactors ?
Coenzymes
What is a substrate (definition).
The reactatanta that are activated by an enzyme.
What determines the specificity of an enzyme.
It’s active site.
What is activation energy (definition).
The minimum input energy required to start a reaction.
How do enzymes affect activation energy ?
Enzymes lower activation energy by creating a new reaction pathway.
What is the lock and key hypothesis.
Substrate and enzyme are complimentary together.
They bond together to form a substrate enzyme complex.
Products have a different shape from the substrate. Mine formed they are released from the active site leaving it free to become attached to another substrate.
What is the induced fit hypothesis.
When a substrate combines with an enzyme it induces a change in the enzyme confirmation. The active site is then moulder into a precise confirmation making the chemical environment suitable for the reaction.
The bonds of the substrate are stretched to make the reaction easier.
Why do we now used the induced fit hypothesis ?
It explains why enzymes can fit with different substrates and also explains activation energy.
Give two was that enzyme catalysed reactions can be measure.
Measure the formation of products
Measure the disappearance of the substance.
When is measuring the formation of products in an enzyme catalysed reaction best.
If the products are gases because they can be easily collected with a gas syringe.
Why is the initial rate of an enzyme catalysed reaction high ?
The initial rate of reaction is high due to a lot of substrate being present. The chances of collusion between enzyme and substrate is high. A lot of enzyme- substrate complex’s are formed.
Why does the rate of reaction of an enzyme catalysed reaction reduce ?
The rate of reaction will later decrease as the concentration of the substrate is a lot lower. Therefore fewer enzyme substrate- complex are formed.
How do you measure the rate of reaction.
Draw a tangent to that point. Then create a triangle to that point.
Find the gradient by doing the change in y divided by the change in x
