Hello Punnett Squares! OOOH, sounds like fun!

Punnett Squares Punnett squares- a method used to establish the probabilities of the results of a genetic cross. Developed by R.C. Punnett (1875-1967). Punnett devised the "Punnett Square" to depict the number and variety of genetic combinations.

Monohybrid cross- a cross between individuals that involves one pair of contrasting traits This example represents the probability of inheriting genes that will result in a purple or white flower.

Some basic rules about completing Punnett squares: Genes occur in pairs: BB, Bb, bb BB- homozygous dominant (pure dominant) Bb- heterozygous (hybrid) bb- homozygous recessive Traits are represented by letters- the capital letter refers to the dominant trait, the small letter refers to the recessive trait. Below we are crossing a heterozygous black mouse with a homozygous white mouse. The black gene is dominant and the white gene is recessive. In a pair of genes the dominant gene occurs first Bb not bB.

Bb bb Using the Punnett square method it can be determined that when a heterozygous black mouse (Bb) is crossed with a homozygous white mouse (bb) there is a 50% chance that there will be a black mouse for each time a mouse is produced and a 50% chance that a white mouse will be produced for each time a mouse is produced. Notice that the chance of producing a black mouse will be one that has the gene for white.

When a heterozygous brown-eyed Hello Kitty is crossed with a homozygous blue-eyed Hello Kitty, there is a 50% or 2 in 4 chance that there will be a blue-eyed Hello Kitty. Bb bb

Bb bb b B Bb bb