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Unformatted text preview: LAB WEEK # 10 EXERCISE # 2-11 THE LETHAL EFFECT OF ULTRAVIOLET LIGHT ON MICROBIAL GROWTH UV wavelength is 254 nm (UV-C) Non-ionizing radiation Damage is the formation of thymine dimers In order for the UV light to be damaging, the exposure must be direct. Materials: 5 TSA plates Serratia marsescens 24 hour nutrient broth Bacillus cereus 7 day nutrient broth* Aspergillus niger 7 day saline broth* Escherichia coli 24 hour nutrient broth What is the purpose of the long term (7 day) broths? Which one is the fungal organism? Inoculate each plate with the four organisms each in their own quadrant. Plate #1 will serve as a negative control and will not be subject to UV radiation. Plate #2 will be exposed without its cover for 1 minute under the UV light. Plates # 3 and plate #4 will be exposed without their covers for 3 and 5 minutes respectively. Plate #5 will get 5 minutes under the UV light except its cover will be left on. Incubate at 37 o C for 24- 48 hours. Which plates might you think will be affected negatively by the application of UV light ? EXERCISE 8-3 BACTERIAL TRANSFORMATION: THE pGLO SYSTEM ( Instruction sheets provided) PLASMID- an extrachromosomal circular piece of DNA that will act as a vector for the transformation of E coli bacteria TRANSFORMATION- bacterial cells will pick up DNA from their environment and will now be capable of gene expression in that DNA COMPETENT- organism will now be capable of picking up that DNA after being subjected to a CaCl 2 solution GFP- green fluorescent protein gene which allows the organisms to glow when exposed to UV light (GFP is responsible for bioluminescence in jelly fish) bla gene- gene which codes for the production of the enzyme, B lactamase which hydrolyzes ampicillin and penicillin. This makes the organism resistant to the ampicillin so that it will grow on media which contains ampicillin promoter- arabinose in the media allows for the bla gene expression....
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This note was uploaded on 10/18/2011 for the course MCB 2010 taught by Professor Elizabethingram during the Fall '11 term at Valencia.
- Fall '11