Genetic Inheritance

This week, we will be learning about dominant and recessive genetic traits, and how an individual's inherited traits are found within their genetic material. This refers to TEKS Science Grade 7-10c.

In this unit, we have talked about genetics. In genetics, we have studied something called heredity, which is the passing of the parent's traits to their offspring. We have also talked about genotypes and phenotypes. The genotype of an individual is their genetic characteristics that we cannot see by looking at the person. Phenotype is the physical characteristics that you can see. We also talked about alleles, which are alternate forms of a gene that are located on the chromosome of an individual.

In this part of the unit, we will be talking about dominant and recessive traits. Dominant traits are traits that are always expressed in an individual. This means that you can always see these traits. For example, brown eyes are dominant over blue or green eyes. So, we know that a person who has brown eyes has at least one dominant allele for brown eyes. Recessive traits are only expressed when two recessive alleles are matched up together.

It is the allele (the alternate form of a gene) that carries the dominant or recessive trait. So, the inherited traits of an individual are found within the genetic material. These traits effect the phenotype of an individual, or their physical characteristics.

Gregor Mendel studied "inheritance," which is the passing on of traits from parents to their offspring. He is known as "the father of genetics," because of his studies and discoveries on inheritance. He used pea plants for his first studies on inheritance.

A very useful tool for determining inheritance is the punnett square. A punnet square is a diagram that helps determine what the offspring of two parents will look like when they are crossed. We used these in class, but this will give you more practice. Remember that lowercase letters mean that the trait is recessive, and capital letters mean that the trait is dominant.

This might still be new to you, but that's ok! Practice doing some punnett squares, and you will have it in no time! (for this activity, only worry about the top part, the part that says "monohybrid cross," we will learn about dihybrid crosses later!)

Here are some more sites that you can practice more with punnett squares! We will do some of these together in class, but go ahead and get some practice on your own too!