Drosophila Lab: Exploring Genetics

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Drosophila Lab Exploring Genetics

• AP recommended lab

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Two Tasks to Complete

• Pre-lab Questions from 12 Recomm. Labs
• (link from my website)
• Computer Simulated Lab Gene Pool drive
• Answer Questions on a separate paper.

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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.

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Key Parts for Drosophila Lab

• Stages of Drosophila
• Main Characteristics to observe (4)
• Determining Male vs. Female (3)
• Examine 3 Modes of Inheritance
• Monohybrid Red Eyes x Sepia Eyes
• Dihybrid Eye color, Wing
• Sex-Linked White eyed-female x Red eyed Male
• (X? X ? ) (X ? y )

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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.

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Crosses to Complete for Lab 6

• Table 7.1 F1 Generation Data

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F2 Generation Sex-Linked trait
Assume that the following Data was obtained and
determine if it is significant or not by
calculating a Chi-Square value.
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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
• ThereforeOur 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).

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2nd Genetic Cross

• Red-Eyed Dominant S
• Sepia eyes Recessive s
• Parental cross SS X ss
• F1 Cross Ss X Ss
• F1 All Ss
• F2 31 (redsepia)

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Observed Values for 7 (table)

• Phenotype Observed Expected
• Red-Eyed 140 calc. value
• sepia 60 calc. Value
• Total 200 offspring
• Complete Questions 6 7

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Data for Second Cross
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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)