#### Related to [[Genotype]] and [[Phenotype]] --- ## Definition - An allele defines **two versions of a gene that code for differing proteins**, one usually comes from mom and one from dad. that codes for a specific trait that can often have variation, *like color of the eyes*. --- ## Dominant vs. Recessive alleles - Dominant alleles *represented by capital letters* take priority over recessive alleles in heterozygotes. This means that if an individual has one recessive and one dominant allele their phenotype will still be the one coded by the dominant allele. >[!tip] >- Its important to know that in perfectly random mating conditions over a long enough period of time **the percentage of dominant vs recessive alleles in a population will not change**. However if there are [[Mating success vs reproductive success|selective pressures]] on a population some alleles may become more common then others. --- ## Calculating traits from alleles - When counting alleles to find the percentage of dominant vs recessive alleles in a population, always remember that there are two copies *(one capital and one lowercase (Ex: rR)*. - Punnett squares are a great way to determine how likely decedents are to have certain traits *or combinations of alleles*. - **A *pure* breading couple means that both animals have the same allele combination** either both recessive or both dominant which **ensures** that their children will also either be all dominant or all recessive. As long as these animals don't bread with other populations the controlled population will become *pure bread* meaning that all its animals will have the exact same combination of either dominant or recessive alleles. >[! Punnett square example] ></br> > >![[punnent square example.png|800]] --- #mainpage