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The Continuity of Life: Cellular Reproduction > Group Activity
Your instructor will choose several traits (such as a widow’s peak, the ability to curl your tongue, and gender) that you can easily evaluate and will show you the appropriate symbols for those traits and which traits are dominant or recessive. If you have the dominant phenotype for a given trait and can’t determine whether you are heterozygous dominant or homozygous dominant, assume that you are heterozygous dominant for that trait. On one side of a strip of paper, label one allele (for example, T); on the other side, label the other allele (say, t, if you are heterozygous). For simplicity’s sake, assume that each allele is on a separate chromosome, so label each trait on separate paper strips; you’ll have as many strips of paper (chromosomes) as traits chosen. Put your initials on each paper strip so that you’ll be able to identify it as yours. Label each strip as chromosome 1, 2, 3, and so on according to the traits assigned. (In other words, each student should show the same trait on the same numbered chromosome.)
Drop your "chromosome 1" strip onto the floor so that the allele that faces up is determined at random. Do the same thing for each trait. The alleles that face up are the ones you’ll pass on to your offspring—one per trait. Record those alleles, indicating the trait for which each applies. Then "mate" with—that is, share chromosomes with—another student. Record your partner’s alleles for each trait. You’ll get pairs of alleles that result from random mating. Then determine the genotype and phenotype of your offspring. If you have time, try to get the results of a few different random matings, and compare them.
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