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quiz3 key - AGRY 320 GENETICS Fall 2007 QUIZ#3 NAME This is...

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AGRY 320 GENETICS Fall 2007 QUIZ #3 NAME ______________________________________________ This is a take home quiz, due at the beginning of class on Wednesday, October 7, 2009. Answer the following questions based on the data provided. To receive full credit, you must show how you determined your answers and your answers must be neat and clearly presented. You may wish to work on scrap paper and transfer your work to clean sheets to make sure your answers are clear and neat. You are encouraged to work with others, but DO NOT simply copy someone else’s work. Please, do not return the background and information pages. Return only the Question and Answer pages (pages 6-8) STAPLED to this cover page.
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BACKGROUND The temperate bacteria phage lambda lives on E. coli bacterial cells. These phage are visible on plates of bacteria as “plaques.” Each plaque is initiated by a single phage infecting a single cell. As that phage, and its chromosome, multiplies it lyses the cell releasing identical phage carrying the same chromosome and those phage infect surrounding cells. This process continues until enough cells have died in that region of the plate that a small area of lysed cells (a plaque) becomes visible. As a temperate phage, lambda normally integrates into the host chromosome and enters a lysogenic life cycle. Occasionally, the phage chromosome exits the host chromosome and enters a lytic life cycle. This behavior causes the formation of turbid plaques (regions of E. coli cell lysis around cells that are still lysogenic). However, certain mutations make it impossible for the phage chromosome to insert into the host chromosome. Lambda phage that carry these mutations have to enter a lytic life cycle. As a result, the plaques they form are clear; i.e., all of the cells that are infected by the mutant phage lyse leaving no lysogenic cells. Lambda phage, therefore, afford us an opportunity to identify the genes that enable phage DNA to integrate into host chromosomes and to discover how those genes function. EXPERIMENT 1 To identify all of the genes that are involved in the process of lambda phage chromosome integration, you have performed a mutagenesis experiment. Lambda phage chromosomes were exposed to ultra violet light, a process known to cause point mutations. These chromosomes,
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quiz3 key - AGRY 320 GENETICS Fall 2007 QUIZ#3 NAME This is...

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