Mendel’s Three Laws

Mendel’s Three Laws

• Mendel was a scientist who developed laws of inheritance.  They are as follows:

1. Law of Dominance: when there are alternate forms of a gene, the gene that will be expressed is the dominant form
2. Law of Segregation: inherited traits are defined by gene pairs, and sex cells contain only one gene of the pair
3. Law of independent assortment: inheritance of one trait is not dependent on the inheritance of the other because traits are arranged separately from each other.

• Beneficial information: http://www.hobart.k12.in.us/jkousen/Biology/mendel.htm
• Genes or traits can be expressed by a capital letter in a Punnett Square.  You take the trait of the mother and the trait of the father and put one on the column and the other on the row.  Lets say that a capital ‘T’ means the child will be taller than average, the lower-case ‘t’ means the child will be shorter than average.  When there is a capital ‘T’, it will be expressed.

Here the trait that is capitalized will be expressed by splitting the genotype letters and putting them on the column, or on the row so you segregate (Law 2) the traits. This forms the possibility that the child will have a 75% chance of being tall and a 25% chance of being short

• Another way of viewing traits is something similar to this diagram as well: