AP Biology/Patterns of Inheritance

In this unit we are going to discuss Patterns of Inheritance.

Punnett square

Understanding how the punnett square is used and how to use it will elevate your understanding of inheritance. It was invented by Reginald Punnett, one of the first geneticists. Biologists use this tool to predict the genotype of an offspring.

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There are two different types of alleles: dominant and recessive. Before we go any further, it is important to understand the terms homozygous and heterozygous. Homozygous refers two a pair of alleles being the same, and heterozygous refers to a pair of alleles being different. For example, BB (two dominant alleles) could be described as Homozygous dominant. Bb, however, would be described as heterozygous dominant, or even heterozygous recessive. A homozygote is an organism the same alleles for a trait, and a heterozygote is an organism with different alleles for a trait.

If an individual's mother and father both had homozygous dominant alleles for a particular trait, then there is a hundred percent chance that they themselves will have homozygous dominant alleles for that trait, thereby making them a homozygote. Mendel’s law of segregation and independent assortment

Mendel's law of segregation means that each parent only contributes one allele to their offspring, and that their offspring possess two alleles.

Mendel's Law of Independent Assortment states the inheritance of one pair of factors (genes/traits/alleles) is independent of the inheritance of the other pair. We know this is true for genes or alleles on the same chromosome.