Coin Sex Lab

In this lab, we flipped coins to simulate the randomness of alleles crossing over and recombination in sex. The coins represented the two copies of a gene, and flipping them simulated the randomness of which gene the gamete would get in meiosis, also known as the law of independent assortment. The results we got for simulating getting a male or female were the same as the expected result, 1/2 probability either way, because the females are homozygous, and don't get to determine the gender, while males are heterozygous, so they determine the gender with the one Y chromosome they have which has a 50% chance of being inherited. We then we simulated a monohybrid cross where we tested the probability of inheritance for an autosomal gene that causes bipolar disorder. Bipolar disorder is caused by a dominant gene, and we crossed a homozygous recessive person with a heterozygous person. We predicted that 50% of the children would have bipolar disorder, but we were wrong when our simulation resulted in 8 normal children and 2 children with bipolar disorder. This shows that the probability of getting a trait is not the same as the ratio of people with the trait, because getting a certain allele is completely random, so it doesn't necessarily follow the probability. The third trait that we tested was colorblindness, an X-linked recessive trait. Males are more likely to inherit X-linked traits because they only have one X chromosome. We crossed a heterozygous female and a male with normal vision. We predicted that 25% of the children will be colorblind males. We found that 3 out of 10 were colorblind males, which is about 25%. Our final cross was a dihybrid cross where we tested hair and eye color. We predicted that there was a 1 out of 16 chance of getting a double homozygous child from 2 double heterozygous parents. Our prediction was correct, and we got that result. All these crosses show how you can predict the probability of having a certain child, but you can't predict what the child will be.