Biological Molecules (Enzymes) Flashcards
What is the purpose of enzymes?
- To speed up reactions in an organism
- To allow them to happen at realistic temperatures by lowering the activation energy
What word describes an enzyme in terms of its place in a reaction?
Catalyst, meaning it does not get used it in the reaction
What is the active site?
The region of the enzyme where the reaction takes place which has a specific shape complementary to the substrate
What is the substrate?
The molecule(s) that the enzyme acts upon to form the products through breakdown or build up
What forms when a complimentary substrate and active site of an enzyme bind together?
- Enzyme-Substrate Complex
- The more of these that form, the higher the rate of reaction
What is the optimum temperature for most enzymes in the human body?
37 degrees celcius
What happens when an enzyme is denatured?
The specific shape of the amino acids change in the active site as the bonds are broken, and the active site is no longer able to fit the substrate. The enzyme ceases to function. This process is not reversible
What happens when an enzyme is at a temperature which is too high?
The enzyme denatures due to the high amounts of kinetic energy
What happens when an enzyme is at a temperature which is too low?
- Due to there being very little kinetic energy and very few collisions, the rate of reaction of the enzyme is extremely slow
- They do not denature
What happens when the temperature of an enzyme is at its optimum?
The rate of reaction is the fastest as they have the most kinetic energy and more collisions will occur without denaturing
Outline an investigation of temperature on enzyme activity
- Add iodine to each well on a spotting tile
- Mix amylase with starch solution
- Every minute, transfer a drop of this solution onto each of the wells
- Record the time it takes for no blue-black colour to be seen
- Repeat by heating up the starch-amylase solution to different temperatures
Use a water bath to heat up the solutions as it is more precise and safer than a bunsen burner
What is the optimum pH for most enzymes?
pH 7
However, some enzymes like like pepsin in the stomach prefer pH 2
What can happen if the pH is too high or low?
It can denature
Why is the enzyme denatured when put in conditions of pH which is too high or low?
The hydrogen and hydroxide ions which change with pH disrupt/destroy the bonds of the enzyme which changes the shape of the amino acids in the active site, meaning it cannot fit with the substrate and activity will cease
Outline an investigation of pH on enzyme activity
- Add iodine to each well on a spotting tile
- Mix amylase with a pH buffer in a test-tube
- Add starch to this solution
- Every minute, add a drop of the solution to each of the wells
- Record the time it takes for no blue-black colour to be seen
- Repeat the experiment with different pH buffers
Keep the temperature, volume and concentration of amylase, iodine and starch solutions the same
