Q9 Enzymes Flashcards
Investigate the effect of pH on the rate of enzyme activity — Method
- Add catalase, pH9 buffer and washing up liquid to a graduated cylinder.
- Add Hydrogen peroxide to a boiling tube.
- Place the boiling tube and graduated cylinder in a water bath of 25°C.
- Wait for both to reach 25°C.
- Take the boiling tube and graduated cylinder out.
- SLOWLY add the hydrogen peroxide down the side of the graduated cylinder.
- Calculate the height of oxygen & water (foam – rate of enzyme activity).
- Record the initial volume and then final volume, after two minutes.
- Repeat this using pH 4, 7, and 10.
Investigate the effect of pH on the rate of enzyme activity — Expected Result
pH 9 was the optimum pH for the enzyme catalase, as it produced the most product.
Investigate the effect of temperature on the rate of enzyme activity — Method
- Add catalase, pH9 and washing up liquid to a graduated cylinder.
- Add Hydrogen peroxide to a boiling tube.
- Stand the graduated cylinder and boiling tube of H₂O₂ in a water bath at 0°.
- SLOWLY add ice cold hydrogen peroxide down the side of the graduated cylinder.
- Calculate the height of oxygen & water (foam – rate of enzyme activity). (Initial volume)
- Record the initial volume and then final volume, after two minutes.
- Repeat the procedure for different temperatures of 25°C, 40°C and 60°C.
- Record results.
Investigate the effect of temperature on the rate of enzyme activity — Expected Result
25°C was the optimum temperature for the enzyme catalase, as it produced the most products: oxygen and water visible as foam.
Investigate the effect of heat denaturation on the activity of an enzyme — Method
- Blend celery with water and filter to extract catalase. Place the catalase in a boiling tube and place in a water bath at 100°C.
- Add the boiled catalase, pH9 and washing up liquid to a graduated cylinder.
- Stand the graduated cylinder and boiling tube of H₂O₂ in a water bath at 25°C.
- SLOWLY add hydrogen peroxide down the side of the graduated cylinder.
- Calculate the height of oxygen & water (foam – rate of enzyme activity).
- Record the initial volume and then final volume, after two minutes.
- Repeat the procedure with unboiled catalase. CONTROL.
- Record results.
What is the chemical nature of enzymes
Protein
What is the enzyme, its source, the substrate, products, control
Enzyme: catalase
Source: celery
Substrate: hydrogen peroxide (H2O2)
Products: water and oxygen which are visible as foam
Control: boiled catalase (except heat denaturation its Unboiled)
What is the purpose of washing up liquid
Trap the oxygen being released which helps form the foam
In PH experiment why is hydrogen peroxide put in water bath
It has come from fridge and needs to be brought up to optimum temperature so that doesn’t affect the PH’s effect on the rate of activity
How do you calculate enzyme rate of activity
Final volume - initial volume after 2 minutes
Volume of foam per minute
PH and temperature/ denaturation experiment: factors kept constant
- Temperature through set water bath at 25 degrees Celsius (PH and denaturation)
- Substrate - same volume and concentration of hydrogen peroxide
- enzyme concentration - same volume of enzyme
- PH - using PH buffer 9 (temp and denaturation)
How do temperature and PH graphs vary
PH graph is very narrow whereas temperature range is much rounder but they are both n shaped
What is the control in the heat denaturation experiment
Unboiled catalase
What is denaturation
The enzymes active site has permanently lost its shape and loses its function
Result of heat denaturation
Boiled catalase produces no foam (no oxygen and water)
Unboiled produces oxygen and water visible as foam
How did you denature enzymes
Place the catalase in a boiling tube and place in a water bath at 100°C
