April 22, 2008

Genes and Dominance

Posted in Genetics tagged , , , , , , at 10:45 am by D. Borst

Why are some genes recessive?

So in genetics class, we learn that Mendel began the study of genetics with his study of peas. One of the notions that he developed was that of Dominant and Recessive genes. But in this age of molecular genetics, what does it mean to be dominant or recessive?

Further inquires into the topic have also led to more controversy. Some genes are “incompletely dominant” and some share “codominance.” Mendel’s Law of independent assortment turned out to not be entirely true. Some traits seemed to be inherited only from the mother.

On the other hand, the discovery that we have a diploid genotype provided a very obvious explanation for the presence of two alleles of a gene, and the nature of meiosis explains why alleles separate during the production of gametes. Today I want to focus on what factors, from a molecular biology standpoint, produce genes that act recessive and dominant. The key is the level of expression.

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