The picture above shows Gregor Mendel also known as "The Father of Genetics". Gregor Mendel made his discoveries about genetics while tending to pea plants. He realized the changes in the colors of pea plant flowers and studied how these changes occur. Gregor Mendel also developed a principle called Medel's Principle of Dominance, which explains how recessive traits can be present and simply not show through because they are masked by dominant traits. This is only true for females, females with a masked recessive trait are known as carriers of that trait. Men can not be carriers because they have one x and one y chromosome, as opposed to two x's. The y chromosome is too small to mask any recessive traits so men are more likely to show a recessive trait. This x and y information only applies to sex linked traits. When organisms reproduce sexually it is called meiosis.
Genetics is the study of heredity and change. Heredity explains how traits are passed from a mother and father to their children. Genes are what code for different versions of traits, these genes are made up of two alleles each. One of the two alleles comes from the father and the other allele comes from the mother.
Cows are perfect examples of co-dominance, co-dominance occurs when there are to dominant genes paired together. Neither gene wants to become recessive so rather than mixing together, they both coexist in equal amounts. A cow is a great example of this because of the different colors that are coexisting on the cow's fur. The cow depicted above had dominant white coloration genes and dominant black coloration genes so they both became co-dominant to each other. The physical expression of these traits or any other traits is called a phenotype. Phenotypes are different from genotypes because an organisms genotype is it's genetic makeup, whereas it's phenotype is the expression of that makeup.
Flowers are great examples of both co-dominance and incomplete dominance. In the case of the picture above, incomplete dominance. Incomplete dominance occurs when two dominant genes combine but, rather than both genes showing through in equal amounts, the genes combine and show through in a mixture. In this case dominant red flower genes mix with dominant white flower genes and the product is a pink colored flower.
A punnett square is the easiest method to use when looking for how traits will be passed on from generation to generation. To complete a punnett square you simply put the first combination at the top of the square and the second combination on the side of the square. Then you fill in the four boxes by putting the top and side factors together. Punnett squares can be used in genetics for sex-linked traits, homozygous (dominant and recessive allele) and heterozygous (two of the same allele) traits, and blood typing. Technically, punnett squares could work for tracking pretty much anything. Blood typing in punnett squares provides more outcomes than any other genetic related punnett square. The crossing of the traits can either be monohybrid, which means that it is being crossed for one desired trait, or dihybrid, which means that it is being crossed for two desired traits.
There are four human blood types: A, B, AB, and O. These four types can turn out to be quite complicated when put into a punnett square however, because of the dominant and recessive alleles. These alleles help determine whether a blood type is negative or positive. Negative and Positive blood type descriptions come from what is called the Rhesus Factor.
The picture above shows a karyotype. Karyotypes allow you to view people's chromosomes. All of the chromosomes above except for the 23rd are called autosomes. The 23rd chromosome determines the person's gender therefore it is known as the sex chromosome. If the 23rd chromosome is xy than it is male and if it is xx than it is a female. The view of people's chromosomes can be helpful when determining whether or not someone is disabled. A sign of a disability is having chromosomes whose bars do not match. If there is an extra chromosome, that means that the person has down syndrome. If the chromosomes do not match, then that is also a sign of a disability.
The final chart used in genetics is a pedigree chart, they are used to track traits throughout generations. The punnett square and pedigree chart are both for simply making it easier to track traits throughout generations. The epigenome makes it easier to read the genes in people, but it is not closely related to the two charts because it is not used for tracking traits.