Lab 1B Report Guidelines

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Indiana University, Bloomington *

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319

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Biology

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Apr 3, 2024

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docx

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L319 Genetics Lab Lab 1B Final Report Guidelines: This report should include all the sections of a full report . Refer to the guidelines for the Lab 1A report for a reminder. You can also reference the sample paper by Frye et al, for a good example. Hopefully by now you are able to incorporate the feedback from your AI into your write-up. Here are some specific guidelines for this report. Experiment 1B Guidelines 1. Within the Results Section: A. Include two tables in your results using the formats shown on page 3 below. The first should present just your data for your six his - mutants. The second should present the summary of the class data in which the total number of each type of mutant (i.e. his1, his2, etc.) obtained in the mutagenized and unmutagenized populations by each lab section is presented. B. Provide a written summary of results. The table cannot stand alone and must be presented in a written format. Include brief explanations of each of the experimental steps performed (e.g. “To test whether my unknown mutants contained mutations in known his genes, I mated each of my mutants (six total) with the his- strains listed in Table 1”). State any conclusions that you can make from the values presented in the Tables (e.g. “I obtained mutations in four different his genes: his2, his3 , his4 , and his6” ). Compare the results of the Tuesday, Wednesday, and Friday Labs (raw data is in the accompanying Excel spreadsheet). C. Perform a chi-squared test on the relative numbers of each type of mutant obtained by the entire class for the 1) unmutagenized population and for the 2) mutagenized population, using the null hypothesis that the frequency of mutations in each his gene will be the same (count his4A, his4B, and his4C and his4ABC mutants as all occurring in the same gene, his4 ). State whether the relative numbers differ significantly from the null hypothesis. 2. Within the Discussion Section: D. Briefly discuss whether your experiment was successful in identifying mutations in his genes, and whether any of your “mutants” turned out to be his + or failed to mate. Discuss any problems (e.g. the his2 tester line appeared to grow on the SD-his plates, making it difficult to score for complementation). If problems arose, suggest a possible cause, and what was done to address the problems. E. Address the results of the chi-squared test and suggest explanations. F. Address the following within the Discussion: 1. Did EMS exposure equally affect all 7 genes in the histidine biosynthetic pathway? If not, why might one gene be more susceptible to EMS mutagenesis than another gene? 2. We might have expected to find a higher frequency of polar mutants (his4A - B - C - ) in the unmutagenized culture compared to the mutagenized culture. Why? What does our actual data tell us? 1
3. What might explain the high number of certain types of his- mutants recovered in this study? The low number of other types of his- mutants? What background research might allow you to predict which mutants we would recover more or less often? Would there be different expectations for mutagenized vs. unmutagenized cultures? 3. Within Other Sections: G. In your Introduction briefly describe the overall goal of the experiment. Also describe the genetic principles that this exercise was designed to demonstrate. Be sure to cite at least one current related reference. H. Write an Abstract (200 words or less) that concisely describes the goal of the experiment, the methods used, the results obtained, and the conclusions drawn. I. In your Materials and Methods , follow the format of the sample journal article posted on Canvas (i.e. do not write it like a lab protocol). Provide citations for the protocol followed. Include details about the strains used! This report must be submitted to Canvas by 9:00 PM on Saturday, March 9 . We will not accept late reports unless you have a valid and documented excuse. Grading This report is worth 100 pts. You will be graded on as follows: • The accuracy of your Tables = 15 pts • The accuracy of your Chi Square Analysis = 15 pts • Your ability to concisely describe the results from your Tables and Chi Square Analysis in your Results section = 10 pts • The quality of your Introduction (including a current reference) = 10 pts • The quality of your Discussion = 10 pts • The quality of your Abstract = 10 pts • Clear, concise Materials and Methods section (written in passive voice) = 10 pts • Overall quality of the your writing (lack of grammatical errors throughout = 10 pts • Proper formatting, including citations = 10 pts 2
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