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Unformatted text preview: Tetraploid Cross Detailed Answer – Discussion Section Handout #7, Question 1c 1) c. Now imagine that peas are tetraploid. What ratio of phenotypes would result from the same cross [the self-cross among the offspring from the true-breeding purple-flowered pea and the true-breeding white-flowered pea]? (Hint: you can assume that each chromosome pairs up with only one other homologous chromosome at metaphase I of meiosis, and that pairing within a set of four homologous chromosomes is random). METHOD 1: I will be using C for the dominant allele (purple flower) and c for the recessive allele (white flower), since this was Mendel's notation according to Dr. Rine. Since the pea is tetraploid and it obtained half of its chromosomes from each of its two parents (true- breeding purple and true-breeding white), we know the flower color alleles it contains must be: CCcc. We are crossing two of these CCcc flowers, so we need to figure out the number of gametes each parent of the cross can make. Meiosis creates gametes with ploidy numbers that are half of the original parent of the cross can make....
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- Spring '11