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    Segregation and allelic frequency

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    1) According to the Law of Segregation, in an organism with the genotype AaBb what types of gametes will be formed?

    AB Ab aB ab

    2) In garden peas, the allele for tall plants is dominant over the allele for short plants. A true-breeding tall plant is crossed with a short plant and one of their offspring is self-pollinated. Out of 20 offspring resulting from the self-pollination, about ________ should be tall.

    TT x tt= Tt x Tt= TT Tt Tt tt ¾=15

    4) Martians normally have three eyes (E), but the rare "humanoid" mutation (e) causes monsters with two eyes to be born. Eye color in Martians is inherited similarly to humans, with brown eyes (B) being dominant to blue (b). Assuming these two genes are carried on separate chromosomes, what must the genotypes of two normal, brown-eyed parents be if they have a blue-eyed, humanoid son?

    EeBb x EeBb

    5). Consider three yellow round peas, labeled A, B and C. Each was grown into a plant and crossed to a plant grown from a green wrinkled pea. Exactly 100 peas from each cross were sorted into phenotypic class as follows:
    A: 51 yellow round, 49 green round
    B: 100 yellow, round
    C: 24 yellow round; 26 yellow wrinkled; 25 green round; 25 green wrinkled
    What were the genotypes of A, B and C?
    Use gene symbols of your choosing; be sure to define each one.
    Y=yellow y=green S-round s-wrinkled

    Cross Genotype
    A YySS
    B YYSS
    C YySs

    6). Phenylketonuria (PKU) is a human hereditary disorder that prevents body from processing the amino acid phenylalanine. PKU is manifested in early infancy and if remain untreated, generally cause mental retardation. PKU is caused by a simple Mendelian recessive allele.
    A couple intends to have children but consults a genetic counselor because the man has a sister with PKU and a woman has a brother with PKU. There are no other known cases in both families. They ask the genetic counselor to determine the probability that their first child will have PKU.
    What is this probability?

    7. What type of cell division is presented on the picture below? How many cells are in anaphase? ( circle them)

    8. Draw mitosis in a cell with 2n=2.

    9. Name three main differences between mitosis and meiosis.
    Mitosis Meiosis

    10. Draw meiosis stages for a cell with 2n=2. Assume that each chromosome carry different allele of gene A.
    Not necessary to include all prophase stages.

    After crossing tobacco plants with purple stem, green leaves and nonpurple stem, yellow leaves, in F2 students observed following results:
    puple stem, green leaves 1297
    nonpurple stem, green leaves 469
    puprle stem, yellow leaves 433
    nonpuprle stem, yellow leaves 164

    Suggest a hypothesis how the traits are controlled and use Chi-square test to test your hypothesis.

    See attached file for full problem description with images.

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    Solution Summary

    Answers to several questions regarding allele segregation and frequency.