LAB REPORT - Sylvia Alamba Biology 112 Lab report July 29,...

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Sylvia Alamba Biology 112 Lab report July 29, 2010 Title: Effects of Temperature and Nutrition on the Population Growth of Escherichia coli Introduction : The purpose of this experiment is to observe which nutrient (yeast extract or nutrient broth) can increase the population of E. coli population in a short amount of time. We measured this growth by using a spectrophotometer; its purpose is to measure the light intensity of the bacteria. Materials and Methods: 1. Four 125 ml flasks 2. Six spectrophotometer test tube (four for sampling, and the other two for blank nutrient broth and blank yeast extract) 3. A spectrophotometer device 4. E. coli strain 5. Yeast extract 6. Nutrient broth 7. Room temperature water bath 8. Gloves 9. Sharpie 10. Tape 11. Pen/ pencil 12. Paper 13. Sterile plastic pipette Green pi-pump 1. For this experiment, our group used a spectrophotometer to measure the bacterial growth by taking optical density readings on the device. We turned it on and let it
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warm up for about 15 minutes. Wavelength was set to 100% and the zero control knob was set to zero. 2. We inserted a blank (for sampling) which was a test tube filled with 2/3 of water and another test tube filled with 2/3 of water and blue dye. We inserted each tube one after another into the sample holder and we set the wavelength to 100% and the zero control knob to zero each time we were done with one tube 3. We began by using four 125 ml flasks and labeling them with tape using a sharpie, “A”, “B”, “C”, and “D”. One of my group members (Terrence) taped each flask towards the top of the flask. And we did this for the spectrophotometer test tubes and the 5 ml pipettes. 4. I then labeled another spectrophotometer test tube “BN” for blank nutrient broth and one test tube “BY” for blank yeast extract with tape at the top of the tubes. 5. As we prepare for our experiment, we were advised to put on gloves for our safety and reduce the chance of adding other contaminating organisms to our cultures. 6.
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LAB REPORT - Sylvia Alamba Biology 112 Lab report July 29,...

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