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Drosophila Lab: Exploring Genetics AP recommended lab Two Tasks to Complete 1. Pre-lab Questions from 12 Recomm. Labs (link from my website) 2. Computer Simulated Lab: “Gene Pool” drive ***Answer Questions on a separate paper. To Access the Lab Simulation for Drosophila • Click the “START” and choose “My Computer” • Type in the following: \\trhs_math_lang\genepool$ • Choose the “Drosophila folder” and double click the “Neo” application. • Follow the instructions and answer the guiding questions listed on the front page of your lab. Key Parts for Drosophila Lab • • • • Stages of Drosophila Main Characteristics to observe (4) Determining Male vs. Female (3) Examine 3 Modes of Inheritance: Monohybrid: Dihybrid: Sex-Linked: Red Eyes x Sepia Eyes Eye color, Wing White eyed-female x Red eyed Male (X? X ? ) • (X ? y ) Observed Values • Table 7.2: F2 Generation -78 red-eyed females -62 white-eyed females -69 red-eyed males -73 white eyed males Expected Results: Complete #3 (both Tables) Do a Chi-square analysis. **Note: Critical values are listed in Table 7.5 on the bottom of Page 86. Crosses to Complete for Lab #6 1) Table 7.1: F1 Generation Data Phenotype and Symbol Red-eyed White-eyed Females Males all XRXr all XrY F2 Generation: Sex-Linked trait Phenotype and Symbol Females Males Red-Eyed (XR) 78 XRXr 69 XRY White-Eyed (Xr) 62 XrXr 73 XrY Assume that the following Data was obtained and determine if it is significant or not by calculating a Chi-Square value. Answer for First Cross X2 = (78-72) 2 + (69-71)2 + (62-71)2 + (73-71)2 71 71 71 71 X2 = 0.69 + 0.06 + 1.14 + 0.06 X2 = 1.94 Degrees of freedom: (4 categories) 3 Critical Value: see Table7.3 (pg.85) 7.82 The chi-squared value is less than 7.82 Therefore:Our null hypothesis is accepted: That there is not a significant difference between the observed value and expected value. We must then accept that our results follows the expected (theoretical value). nd 2 • • • • • • Genetic Cross Red-Eyed: Dominant Sepia eyes: Recessive Parental cross: F1 Cross: F1: F2: S s SS X ss Ss X Ss All Ss 3:1 (red:sepia) Observed Values for #7 (table) Phenotype Red-Eyed sepia Total: # Observed 140 60 200 offspring Complete Questions #6 & 7 # Expected calc. value calc. Value Data for Second Cross Phenotype # observed (o) # Expected (e) (o-e) (o-e)2 (o-e)2 e Red 140 Sepia 60 Other Crosses to do • Pg 86: Green & Albino seedlings • Pg.88: Long & short winged flies **complete and calculate Chi-Square values to determine if the results are significant and acceptable (statistically valid)