Enzymes Flashcards
What is a catalyst?
A catalyst is a substance which increase the speed of the reaction, without being changed or used up in the reaction
What are enzymes made out of?
-Enzymes are all proteins, and all proteins are made up of chains of amino acids
What is the role of an enzyme?
- A biological catalyst in metabolic reactions
- Specific
- They are reusable
- The substance the enzyme acts on is the substrate (which is a molecule that is changed in a reaction)
- The substance binds to the active site and forms the enzyme substrate complex
What affects enzyme rate of reaction?
- pH
- Temperature
- Enzyme concentration
- Substarte concentration
- Surface area of the substrate or area
How does pH affect enzyme rate of reaction?
- Enzymes have an optimum pH (every enzymes has its own pH), and it can denature if it is far away from that pH
- The pH interferes with the bonds holding the enzyme together, this changes the shape of the active site and dentures the enzyme
How does enzyme concentration affect enzyme rate of reaction?
More enzymes means faster rate
How does temperature affect enzyme rate of reaction?
- As temperature increase so does the enzyme rate of reaction until about 40 degrees
- This is because more heat means the enzymes and the substrate particles have more energy. This makes the enzymes and substrate particles move about more , so they have a higher collision rate
- However at 40 degrees, the bonds holding the enzyme will break and they begin to change shape and its active site doesn’t fit the shape of the substrate anymore (the enzyme substrate complex cannot be achieved), this means that it cannot catalyse the reaction anymore and the reaction stops. The enzyme cannot function and is denatured. Its change in shape is irreversible (permanent)
- Each enzyme has its own optimum temperature when the reaction goes fastest. This is the temperature just before it gets too hot and starts to denature. The optimum temperature for the most important human enzymes is about 37 degrees Celsius, the same temperature as our bodies
How does substrate concentration affect enzyme rate of reaction?
More substrate means faster until all active sites are in use at any point
How does SA of substrate/or area affect enzyme rate of reaction?
Increased SA means increased rate because there is more space for the enzymes to work over
What is one way to measure the effect of temperature on enzyme activity?
- The enzyme catalase catalyses the breakdown of hydrogen peroxide into hydrogen and oxygen
- Measure the amount of oxygen produced is a set period of time e.g. minuet
- Change the temperature of the water bath and see at which temperature the most oxygen was produced in a set period of time
- Control Variables: enzyme concentration, pH, volume of solution, making it a fair test
What is the second way to measure the effect of temperature on enzyme activity?
- The enzyme amylase, catalyses the breakdown of starch to maltose
- It is easy to detect starch the substrate by using iodine solution, if starch is present the solution with change from brown to blue-black
- You can time how long it will take for the starch to disappear by regularly sampling the starch solution, and use the times to test to compare rates between different tests
- By adjusting the water bath temperature, you can see how temperature affects the activity of amylase
- Control all variables
