Coin Sex Lab

In this lab we learned how to use punnet squares to predict what traits our offspring will have, and how these prediction can deffer from what actually will happen. In this lab we used coins to represent genes, and the two sides of the coin represent the two different alleles for the gene. The flipping of the coins represents meiosis, and the two sets of coins up represents the processes of recombination. The coins also showed how probability of something happening can be different from what actually happens. We did multiple autosomal crosses, where the sex chromosomes are not involved, and one x-linked cross, which is when the sex chromosome are involved. We used two sets of one coin each to represent monohybrid crosses, and two sets of two coins each to represent dihybrid crosses. In some of our tests we labeled both side of the coin the same way to represent a homozygous trait, but in others we labeled the two sides differently to represent a heterozygous trait.

When we preformed the di-hybrid cross, we got results that were slightly different than what was expected. The punnet square gave us a phenotype ratio of:

9 Brown Hair, and Brown eyes : 3 Blond Hair, and Brown eyes : 3 Brown Hair, and blue eyes :
1 Blond Hair, and Blue eyes

Our experiment had slightly different results, and gave us the phenotypic ratio of:

8 Brown Hair, and Brown eyes : 4 Blond Hair, and Brown eyes : 2 Brown Hair, and blue eyes :
2 Blond Hair, and Blue eyes

The slight difference between the probability, and what actually happened is due to the fact that probability, and reality do not always line up. It possible to cross two heterozygotes, and get two recessive alleles in all ten offspring for the same reasons that you can flip a coin ten times and get heads every time. This lab demonstrated the limits of probability. Probability can give you odds on what can happen, but until the event occurs you have no idea what will happen. Relating back to the coin, the probability of getting heads two heads in a row is a 25% chance, but until you flip the coin twice you can't know if you will get two heads.

This lab relates to me because if/when I have children, then I cant use probability to predict what they might be like, but I have no way to know for sure what traits they will have, until they are born.