FRUIT FLY PROBLEMS HEREDITY

Transcription

1 AP BIOLOGY HEREDITY ACTIVITY #7 NAME DATE HOUR FRUIT FLY PROBLEMS The letters and symbols used to represent genotypes in fruit flies are different that what is used to represent the genotypes of other organisms. For this lab you will need to use the following key when representing the genotypes of the flies involved in the crosses: KEY: + Wild (red) type SE Sepia (brown) eyes W White eyes VG Vestigial Wings PROBLEM A: CROSS BETWEEN FEMALE WITH WILD EYES AND A MALE WITH SEPIA EYES P Generation Female Wild Eyes Male Sepia Eyes F 1 Generation Female Male Wild Eyes Wild Eyes N = 5012 N = 4995 Heredity Activity #7 page 1

2 F 2 Generation Female Male Female Male Wild eyes Wild eyes Sepia eyes Sepia eyes N = 3676 N = 3748 N = 1286 N = Be sure that you provide the genotypes for all flies in the diagrams on previous page. 2. What mutation(s) were you following in this cross? (NOTE: Wild type is not a mutation. It is the normal condition in flies. The sex of the fly is not a mutation either.) 3. Examine the data for the F 1 Generation and F 2 Generation results. Make a hypothesis about the pattern of inheritance in this cross by answering the following questions: a. Is the cross autosomal or sex-linked? Autosomal inheritance involves alleles on chromosomes other than the sex chromosomes. Sex-linked inheritance involves alleles found on the X chromosome. To answer this question you need to compare the number of males with a certain characteristics (wild eyes for example) with the number of females. If there is no significant difference between the numbers would you expect the pattern of inheritance to be autosomal or sex-linked? b. Is(are) the mutation(s) dominant or recessive? c. Is the cross monohybrid or dihybrid? To answer this question you need to consider the number of mutations being tracked through the crosses. Heredity Activity #7 page 2

3 4. Using the key on page 1 and the answers to the previous question, construct a Punnett square to predict results of the P (parental) cross and the F 1 cross. If you are sure that the cross is not sex-linked, you should combine the male and female numbers for the same phenotypes. P Cross: x (female genotype) (male genotype) Punnett Square: F 1 Cross: x (female genotype) (male genotype) Punnett Square: 5. According to the Punnett square results, what are the expected phenotypic ratios of the F 1 and F 2 offspring? If you are sure your cross is not sex-linked, you should combine the male and female data for the same phenotypes. CROSS EXPECTED PHENOTYPIC RATIO F 1 F 2 Heredity Activity #7 page 3

4 6. Look at the results of the F 2 generation. How many total flies were produced in this cross? 7. Calculate the number of individuals you would expect to be produced from this cross. To do this you need to multiply the expected ratio (or percent) by the total number of flies produced in the cross. If you are sure that your cross is not sex-linked, you should combine the male and female data for the same phenotype. PHENOTYPES Expected Ratio or Percent EXPECTED NUMBER 8. Calculate the chi-square value for the F 2 generation in the space below. You must show all work. 2 2 ( o e) χ = e χ 2 = Heredity Activity #7 page 4

5 9. Use the Chi-Square Distribution Table below to determine the percent probability that the observed variation is due to random chance alone. Degrees of freedom = % Probability = CHI-SQUARE DISTRIBUTION TABLE Accept Hypothesis Reject Hypothesis Probability (p) Degrees of Freedom Was the deviation between the expected and observed data due to chance alone? How do you know? 11. Based on the answer to the previous question, should you accept or reject your hypothesis regarding the pattern of inheritance for this cross? Explain. Heredity Activity #7 page 5

6 PROBLEM B: CROSS BETWEEN FEMALE WITH WILD EYES & VESTIGIAL WINGS AND A MALE WITH SEPIA EYES AND WILD WINGS P Generation Female Wild Eyes Vestigial Wings Male Sepia Eyes Wild (normal) Wings F 1 Generation Female Male Wild Eyes Wild Wings Wild Eyes Wild Wings N = 5003 N = 5080 F 2 Generation Female Male Female Male Wild eyes Wild wings Wild eyes Wild wings Sepia eyes Wild wings Sepia eyes Wild wings N = 2805 N = 2797 N = 974 N = 959 Female Male Female Male Wild eyes Vestigial wings Wild eyes Vestigial wings Sepia eyes Vestigial wings Sepia eyes Vestigial wings N = 956 N = 872 N = 337 N = 301 Heredity Activity #7 page 6

7 12. Be sure that you provide the genotypes for all flies in the diagrams on the previous page. 13. What mutation(s) were you following in this cross? (NOTE: Wild type is not a mutation. It is the normal condition in flies.) 14. Examine the data you collected form your crosses (F 1 Generation and F 2 Generation results). Make a hypothesis about the pattern of inheritance in this cross by answering the following questions: a. Is the cross autosomal or sex-linked? b. Is(are) the mutation(s) dominant or recessive? c. Is the cross monohybrid or dihybrid? 15. Using the key on page 1 and the answers to the previous question, construct a Punnett square to predict results of the P (parental) cross and the F 1 cross. If you are sure that the cross is not sex-linked, you should combine the make and female numbers for the same phenotypes. P Cross: x (female genotype) (male genotype) Punnett Square: Heredity Activity #7 page 7

8 F 1 Cross: x (female genotype) (male genotype) Punnett Square: 16. According to the Punnett square results, what are the expected phenotypic ratios of the F 1 and F 2 offspring? If you are sure your cross is not sex-linked, you should combine the male and female data for the same phenotypes. CROSS EXPECTED PHENOTYPIC RATIO F 1 F Look at the results of the F 2 generation. How many total flies were produced in this cross? Heredity Activity #7 page 8

9 18. Calculate the number of individuals you would expect to be produced from this cross. To do this you need to multiply the expected ratio (or percent) by the total number of flies produced in the cross. If you are sure that your cross is not sex-linked, you should combine the male and female data for the same phenotype. PHENOTYPES Expected Ratio or Percent EXPECTED NUMBER 19. Calculate the chi-square value for the F 2 generation in the space below. You must show all work. 2 2 ( o e) χ = e χ 2 = Heredity Activity #7 page 9

10 20. Use the Chi-Square Distribution Table from question #9 to determine the percent probability that the observed variation is due to random chance alone. Degrees of freedom = % Probability = 21. Was the deviation between the expected and observed data due to chance alone? How do you know? 22. Based on the answer to the previous question, should you accept or reject your hypothesis regarding the pattern of inheritance for this cross? Explain. PROBLEM C: CROSS BETWEEN FEMALE WITH WILD EYES AND A MALE WITH SEPIA EYES P Generation Female White eyes Male Wild eyes Heredity Activity #7 page 10

11 F 1 Generation Female Male Wild eyes White eyes N = 5019 N = 5008 F 2 Generation Female Male Female Male Wild eyes Wild eyes White eyes White eyes N = 2579 N = 2454 N = 2545 N = Be sure that you provide the genotypes for all flies in the diagrams on pages 10 and What mutation(s) were you following in this cross? (NOTE: Wild type is not a mutation. It is the normal condition in flies.) 25. Examine the data you collected form your crosses (F 1 Generation and F 2 Generation results). Make a hypothesis about the pattern of inheritance in this cross by answering the following questions: a. Is the cross autosomal or sex-linked? b. Is(are) the mutation(s) dominant or recessive? c. Is the cross monohybrid or dihybrid? Heredity Activity #7 page 11

12 26. Using the key below and the answers to the previous question, construct a Punnett square to predict results of the P (parental) cross and the F 1 cross. If you are sure that the cross is not sex-linked, you should combine the make and female numbers for the same phenotypes. P Cross: x (female genotype) (male genotype) Punnett Square: F 1 Cross: x (female genotype) (male genotype) Punnett Square: Heredity Activity #7 page 12

13 27. According to the Punnett square results, what are the expected phenotypic ratios of the F 1 and F 2 offspring? If you are sure your cross is not sex-linked, you should combine the male and female data for the same phenotypes. CROSS EXPECTED PHENOTYPIC RATIO F 1 F Look at the results of the F 2 generation. How many total flies were produced in this cross? 29. Calculate the number of individuals you would expect to be produced from this cross. To do this you need to multiply the expected ratio (or percent) by the total number of flies produced in the cross. If you are sure that your cross is not sex-linked, you should combine the male and female data for the same phenotype. PHENOTYPES Expected Ratio or Percent EXPECTED NUMBER Heredity Activity #7 page 13

14 30. Calculate the chi-square value for the F 2 generation in the space below. You must show all work. χ 2 = 31. Use the Chi-Square Distribution Table from question #9 to determine the percent probability that the observed variation is due to random chance alone. Degrees of freedom = % Probability = 32. Was the deviation between the expected and observed data due to chance alone? How do you know? 33. Based on the answer to the previous question, should you accept or reject your hypothesis regarding the pattern of inheritance for this cross? Explain. Heredity Activity #7 page 14