4 - Enzymes Flashcards
What are enzymes?
Proteins that function as biological catalysts. (because they are made in living cells, and they speed up the rate of chemical reactions without being changed)
What is a substrate?
A molecule that gets broken down or joined together in the reaction with an enzyme.
Why are enzymes specific to one particular substrate?
Because the enzyme is a complementary shape to the substrate (lock and key)
What is the effect of increasing temperature to more than optimum on enzyme function?
Heating enzymes to temperatures beyond optimum will break the bonds that hold the enzyme together and it will lose its shape - known as denaturation. This is irreversible.
What temperature do enzymes work fastest at?
The optimum temperature in the human body, 37 degrees Celsius.
What is the effect of increasing temperature to optimum from zero on enzyme function?
It increases the activity of enzymes as the more energy the molecules have, the faster they move, and the number of collisions with the substrate molecules increases, leading to a faster rate of reaction. - Lower temperatures don’t denature, just slow the rate of reaction.
What is the optimum pH for most enzymes?
7, but some that are produced in acidic conditions (e.g. stomach) have a lower optimum (2), and some that are produced in alkaline conditions (e.g. duodenum) have a higher optimum (8/9)
What occurs if the pH is too high or low?
The bonds that hold the amino acid chain together to make up the protein can be destroyed. That will change the shape of the active site, so the substrate can’t fit into it, reducing rate of reactivity. Moving too far away from optimum pH can lead to denaturation.
