Monday, October 31, 2016

Codominance- Incomplete Dominance -Multiple alleles

When Mendel studied traits the traits what he studied were influenced by only one gene or two alleles. Since then geneticists have discovered traits that are influenced by multiple alleles, genes, and some are even codominant

In this video I would like to talk about incomplete dominance, codominance, multiple alleles, and polygenic inheritance. When you cross a four oclock flower or a snap dragon you have an example of incomplete dominance. In other words both traits show up or mix together.When you cross a white and red flower you get a pink flower.

If you cross the pink flowers you could get white red or even pink. With codominance both alleles show up in the phenotype.

Check out this Punnett square of these two cows. The white and brown color are both dominant and therefore they both appear. They don't blend, but instead both show up. This cow is an example of incomplete dominance, and a speckled chicken

Sometimes more you have multiple alleles that control a trait. With human blood type the blood type is controlled by three alleles.

In this chart you will see that type a and type b are controlled by multiple alles. Finally, some traits are controlled by multiple genes,called polygenic inheritance .In humans our height, skin color, and eye color are controlled by multiple genes.As a result you have many more types of phenotypes.

In summary

Codominance you have mixing or blending of alleles

Incomplete dominance  both traits appear

In multiple alleles traits have more than two alleles.

Finally, polygenic inheritance a trait is controlled by multiple genes..