+=dominat = recessive WEEK 5: Page 11 6. On the basis of the class data in Tables 5-10 and 5-11, circle the most likely pattern of inheritance of the gene for eye colour. Substantiate your answer with specific observations from the data. 3 marks Circle the most likely pattern: Substantiating observations: X-linked or Autosomal 9. Using class data in Tables 5-4 and 5-5 for the observed distributions of F$_2$ phenotypes in cross A and in cross B, perform $\chi^2$ tests to substantiate a mode of inheritance for the gene for eye colour. 10 marks a. Hypothesis ($H_0$): b. Prediction: Table 5-12: $\chi^2$ tests with F$_2$ generation phenotypes for eye colour observed in crosses A and B. CROSS OBSERVED DISTRIBUTIONS (O) EXPECTED DISTRIBUTIONS (E) OF PHENOTYPES OF PHENOTYPES red white red white $\chi^2$ value Critical $\chi^2_{0.05}$ ACCEPT / REJECT $H_0$ $\delta^s$ $\delta^s$ $\delta^s$ $\delta^s$ $\delta^s$ $\delta^s$ $\delta^s$ $\delta^s$ cross A F$_2$ cross B F$_2$ (reciprocal) 10. Can you accept or must you reject the hypothesis ($H_0$) stated in 9a.? Explain. 3 morks Biology 207 Lab Manual
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To do this, we can look at the class data in Tables 5-10 and 5-11 and circle 3 marks for eye color. Based on these observations, we can then substantiate our answer. Show more…
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Sample Crosses Cross C: The genotypes and phenotypes of the true-breeding, parental generation (P₁) in this cross are: se⁺se⁺; vg⁺/vg⁺ (red, complete) x se/se ; vg/vg (sepia, vestigial) Genotype of the F₁ generation is se⁺/se; vg/vg⁺. Phenotype of the F₁ generation is red, complete. Cross D: The genotypes and phenotypes of the true-breeding parental generation (P₁) in this cross are: pkn⁺/pkn⁺; vg/vg (red, vestigial) x pkn/pkn; vg⁺/vg⁺ (pumpkin, complete) Genotype of the F₁ generation is pkn⁺/pkn; vg/vg⁺. Phenotype of the F₁ generation is red, complete. Note: The phenotypes for eye colour and wing type in crosses C and D are not dependent on which parent is mutant. Therefore, the sexes of the parents in the two crosses are not specified. For each of the dihybrid crosses C and D, flies from the F₂ generation, a testcross generation, as well as the reciprocal testcross generation will be scored for eye colour and for wing phenotype. In all, results from six generations (Table 6-1) are presented. Table 6-1: Descriptions of the generations for which results are presented. label generation C1 F₂ (F₁ ♀ x F₁ ♂) Cross C: se⁺/se⁺; vg⁺/vg⁺ x se/se; vg/vg C2 testcross (F₁ ♀ x tester ♂) C3 testcross (F₁ ♂ x tester ♀) D1 F₂ (F₁ ♀ x F₁ ♂) Cross D: pkn⁺/pkn⁺; vg/vg x pkn/pkn; vg⁺/vg⁺ D2 testcross (F₁ ♀ x tester ♂) D3 testcross (F₁ ♂ x tester ♀)
Katlin K.
Analyze cross results Cross 1 - sepia x wildtype (monohybrid) Use the virtual fly lab to create a monohybrid cross between a wild-type male fly and a female fly with sepia eyes. Observe the F1 offspring. Which allele is dominant (sepia or wild type)? How do you know? Mate F1 male and female flies from this cross to produce the F2 generation. Draw a diagram of the parental and F1 crosses you just performed, showing the genotypes of the mated flies and expected ratios of each phenotype among the offspring in each generation. Use the program to perform a Chi-square analysis testing whether the numbers of offspring of each type you observed in the F2 generation fit the ratios predicted by the cross. You may want to click "Ignore Sex" in the upper left to simplify the results reporting if the phenotype numbers appear fairly equal between males and females. Repeat the chi-square analysis with a new ratio until you discover a ratio that will not be rejected. What did you discover to be the correct phenotypic ratio for this experiment?
Use the data in the table below to answer questions 24-26. In the fruit fly, Drosophila melanogaster, the normal eye color is red, but several other eye colors exist. In an analysis of a strain of flies in which eye color is red or dark, several individuals of known phenotype but unknown genotype were crossed. The outcome of the crosses is shown below. These are actual data, so remember that random sampling error may affect the results. Parental phenotypes | Offspring phenotypes | | Dark eye | Red eye | | :--- | :--- | :--- | | 1. dark x red | 10 | 0 | | 2. red x red | 0 | 11 | | 3. red x dark | 6 | 5 | | 4. dark x dark | 10 | 0 | | 5. dark x dark | 8 | 3 | 24. Is the dark-eye allele dominant or recessive? a. dominant b. recessive 25. What is the genotype of the red fly in cross 1? a. AA b. Aa c. A_ d. aa 26. What is the genotype of the dark fly in cross 3? a. AA b. Aa c. A_ d. aa 27. You are breeding pea plants, following a trait with a simple dominant:recessive mode of transmission. If R is the dominant allele and r is the recessive allele, and you cross a true breeding plant with the dominant phenotype and a true breeding plant with the recessive phenotype, what is the genotype of the F1? a. RR b. Rr c. rr 28. Continuing with the scenario in number 27, you backcross the F1 to the parent with the dominant phenotype, what are your results with respect to phenotype? a. All dominant b. All recessive c. ½ dominant and ½ recessive d. ¾ dominant and ¼ recessive
Bryan V.
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