Unit 13 P5 Applied Science
P5 - use laboratory methods to investiate aators that afeat the
enzyme rate o reaatonn
Pepsin is an enzyme present in the juices secreted by the glands in the stomach walls (gastric juice).
Gastric juice contains hydrochloric acid which has a PH 2. The functon of it is to destroy harmful
bacteria that may be present in the food, also provides the optmum PH for pepsin to work. Pepsin
type of protease called endopeptdase. The pepsin hydrolyses peptde bonds within polypeptde
molecules. Pepsin hydrolyses large polypeptdes into smaller polypeptde chains, but does not
release amino acids.
Equipment listn
- Goggles
- Test tube
- Biurette A (NaOH)
- Biurette B (Copper Sulphate)
- Syringe
- Pipette
- Beakers
- Water bath with the temperature of 37 degrees
- Stop clock
Methodn Biuret test or proteinsn
- Add 5 ml of Albumen protein into the test tube using the syringe.
- Put 1 cm3 of Biurette A (NaOH) and give the test tube some heat by holding the tube with a
hand.
- Then add drop by drop of the biurette B which is copper sulphate, the colour change from
blue to purple will appear.
- Observe the increase of the formaton of the purple precipitate indicatng the presence of
protein. Optmum conditons for experiment imitatng the conditons present in the
stomach.
Methodn Conditons and aators afeatni enzyme reaatonsn
1. Place 5 test tubes into the test tube rack. Prepare the water bath.
2. Place 10 ml of Albumen into 5 tubes.
3. Label all of the test tubes with numbers 1-5.
4. Then add 2ml of hydrochloric acid and 2 ml of Pepsin into the test tube 1.
5. Place 2 ml of dilute water and 2ml of pepsin into the test tube 2.
6. Put 2 ml of Sodium Hydrogen Carbonate and 2 ml of pepsin into the tube 3.
7. Put 4 ml of hydrochloric acid into the test tube 4 (use as a comparing sample).
8. Put a boiled pepsin and 2 ml hydrochloric acid into the tube 5.
9. As soon as the pepsin is placed into the test tube, put the rack with test tubes into the water
bath and start the stop clock.
10. Make sure you record the results and check to see the colour change every minute.
P5 - use laboratory methods to investiate aators that afeat the
enzyme rate o reaatonn
Pepsin is an enzyme present in the juices secreted by the glands in the stomach walls (gastric juice).
Gastric juice contains hydrochloric acid which has a PH 2. The functon of it is to destroy harmful
bacteria that may be present in the food, also provides the optmum PH for pepsin to work. Pepsin
type of protease called endopeptdase. The pepsin hydrolyses peptde bonds within polypeptde
molecules. Pepsin hydrolyses large polypeptdes into smaller polypeptde chains, but does not
release amino acids.
Equipment listn
- Goggles
- Test tube
- Biurette A (NaOH)
- Biurette B (Copper Sulphate)
- Syringe
- Pipette
- Beakers
- Water bath with the temperature of 37 degrees
- Stop clock
Methodn Biuret test or proteinsn
- Add 5 ml of Albumen protein into the test tube using the syringe.
- Put 1 cm3 of Biurette A (NaOH) and give the test tube some heat by holding the tube with a
hand.
- Then add drop by drop of the biurette B which is copper sulphate, the colour change from
blue to purple will appear.
- Observe the increase of the formaton of the purple precipitate indicatng the presence of
protein. Optmum conditons for experiment imitatng the conditons present in the
stomach.
Methodn Conditons and aators afeatni enzyme reaatonsn
1. Place 5 test tubes into the test tube rack. Prepare the water bath.
2. Place 10 ml of Albumen into 5 tubes.
3. Label all of the test tubes with numbers 1-5.
4. Then add 2ml of hydrochloric acid and 2 ml of Pepsin into the test tube 1.
5. Place 2 ml of dilute water and 2ml of pepsin into the test tube 2.
6. Put 2 ml of Sodium Hydrogen Carbonate and 2 ml of pepsin into the tube 3.
7. Put 4 ml of hydrochloric acid into the test tube 4 (use as a comparing sample).
8. Put a boiled pepsin and 2 ml hydrochloric acid into the tube 5.
9. As soon as the pepsin is placed into the test tube, put the rack with test tubes into the water
bath and start the stop clock.
10. Make sure you record the results and check to see the colour change every minute.
