Enzymes Flashcards
How do enzymes speed up reactions?
They lower the activation energy and provide a different reaction pathway.
How do enzymes lower the activation energy in the breakdown of a substrate?
They form enzyme-substrate complexes. When the substrate fits into the active site that puts a stain on the bonds of the substrate making them easier to break.
How do enzymes lower the activation energy in the joining of substrates?
When an enzyme-substrate complex is formed the substrates are held close together which decreases any repulsion between them and makes it easier for them to bond.
What is the lock and key model?
The shape of the active site is only complementary to one substrate and when they collide with enough energy the substrate fits perfectly into the active site to form an enzyme-substrate complex.
What is the induced fit model?
When the enzyme and substrate collide with enough energy the active site will change shape slightly so it fits better around the substrate.
Why are enzymes so specific?
Enzymes have a specific tertiary structure meaning that the active site is only complementary to one substrate, This means it can only form an enzyme-substrate complex with that substrate.
What effect does a change in temperature have on the rate of enzyme activity?
If the temperature is too low the particles will have less energy meaning they will move slower and there will be less frequent and successful collisions. This leads to the formation of fewer enzyme-substrate complexes and a decrease in enzyme activity. If the temperature is too high the hydrogen bonds that hold the enzyme together break and that causes the active site to change shape. The denaturing of the active sites means that no enzyme-substrate complexes form and the rate of enzyme activity decreases.
What effect does a change in pH have on the rate of enzyme activity?
All enzymes have an optimum pH. If the pH becomes too acidic or alkali that causes the active site of the enzymes to change shape meaning enzyme-substrate complexes can no longer form.
What effect does a change in substrate concentration have on the rate of enzyme activity?
As the substrate concentration increases the rate of enzyme activity increases because there are more particles per unit of volume and that leads to more frequent and successful collisions. Increasing the concentration above a certain point will have no effect as all the substrates will have bound to an active site and no more enzyme-substrate complexes will form.
What effect does a change in enzyme concentration have on the rate of enzyme activity?
As the enzyme concentration increases the rate of enzyme activity increases because there are more particles per unit of volume and that leads to more frequent and successful collisions. Increasing the concentration above a certain point will have no effect as all the substrates will have bound to an active site and no more enzyme-substrate complexes will form.
What effect does competitive inhibition have on the rate of enzyme activity?
The inhibitors have a similar shape to the substrate so they bind to the active site of the enzyme; preventing the substrate from binding to it and forming an enzyme-substrate complex from forming.
How do we decrease the effects of competitive inhibition?
Increase the substrate concentration to increase the chances that the substrate will bond to the active site before the inhibitor.
What effect does non-competitive inhibition have on the rate of enzyme activity?
They bind to another site on the enzyme and cause the active site to change shape meaning a substrate can no longer bind to the active site and form an enzyme-substrate complex.
