Over the past few days we've learned a whole lot about genetics. We figured out that specific traits that one possesses are not a cross between the traits of his or her parents or just random but actually determined by the combination of genes and alleles. There are two kinds of alleles: dominant and recessive. Two dominant alleles paired together is called a homozygous dominant pair and this will obviously express the dominant trait. A dominant allele paired with a recessive allele also known as a heterozygous pair will express the dominant gene or trait but still carry the recessive trait so that it may be expressed in future generations. The only way for a recessive gene to be expressed is when there is a homozygous recessive pair or a pair of two recessive alleles. We did several different tests both in class and at home to see which traits different people possess and, based on their parents traits, what their genotype is for that trait or what is the allele pair that they have. Weather one possesses a certain trait or not and which kind of trait it may be is known as his or her phenotype. Below is a chart that shows the different phenotypes and genotypes of me and my family.
Based on the phenotypes for each trait of each of my family members, I was able to determine their genotype for each trait because each allele pair is one of the alleles from your mother's pair for that trait and one from your father's pair for that trait. Based on the different combinations possible for my brother and I from my mother and father's allele pairs, I could tell what genotypes we have. For some of the traits however, I was not able to figure out the genotypes because for dominant traits that are present or recessive traits that are not present there are two options for allele pairs and the trait in my parents did not help me figure out which pair each person had for these traits. I also decided to test for thumb crossing when one intertwines their fingers. This is a trait that I learned was genetic on the internet and decided to see which thumb each family member puts on top when they intertwine their fingers. I got the results similar to my Hitch-Hiker thumb results with my mom and I going left over right and my father and brother vice versa. This means that my mother and I are heterozygous for this trait while my father and brother are homozygous recessive because left over right is a dominant trait. I think it is really cool how you can figure out ones genotype based on the phenotypes of them and their family and how traits are passed down through Mendelian genetics.
