This week we have been learning about Genetics. Specifically allele combinations. An allele is an expression of a gene, and they are expressed in sets of two. There are three types of allele pairs. Each allele gets one gene from one parent and one from the other. The three types are homozygus dominant (GG), this type of allele combination will express the dominant trait, whatever it may be; heterozygus (Gg),this will also express the dominat trait; and homozygus recessive (gg), this is the only allele combination that will express the recessive trait. Part of genetics and allele combinations is that you can cross the the two traits and se what type of off-spring an organism may have. The crossing of one trait is called a monohybrid cross. By crossing allele combinations we can dtermine an organisms genotype and phenotype. An organisms genotype is it's allele combination (GG,Gg, or gg). An organisms phenotype is what it looks like (brown hair, blue eyes, ect.) To figure out the results of a monohybrid cross one can make a Punnett Square.
In the Punnett Square above they are comparing two heterozygus parents. Their off-spring have a 3:1 chance of expressing the dominant triat of which is being compared.
In class we did an experiment where we tested our family members on certain traits that they may or may not have. We also tested ourselves. Then we looked up wether certain traits were dominant or recessive. This helped us figure out our genotypes, and our parents genotypes. I tested my sister (Laura), my mom, my dad, and myself. The traits that I tested are wether or not someone can role their tongue, wether someone has a widows peak, has earlobes that are attached or unattached, and if they have a hitch hikers or non hitch hikers thumb. These are the results:
After getting this information I researched the four different traits to see if they are dominant or not, so that I can find out the genotypes of each of my family members and make a pedigree. From my research I found out that being able to roll your tongue, having an unattached earlobe, having a widows peak, and having a non hitch hikers thumb are dominant traits. From this information I can determine each persons genotype, and I can make a pedigree for each of the different traits.
Having a widows peak is a dominant trait. Laura doesn't have one, and I do. For Laura to be my sister, and my parents child (which she is) my Dad's genotype has to be Ww (heterozygus), and my mom's genotype has to be ww (homozygus recessive). They have to be this because if my dad was WW then none of his children could not have a widows peak, making it so Laura can't be his child, but she is. Laura's genotype is ww because she doesn't have a widows peak, and mine is Ww because I have one. Since I am a Ww I express the dominant gene (having a widows peak), but I carry the recessive gene (not having a widows peak). So depending on who I marry, my children may not have a widows peak. The rest of the genotypes for each trait are:
Knowing wether a certain trait is dominant or recessive is key in being able to figure out someone's genotype. I encourage you to go home and see if you can figure out your families genotype!
