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Famous Biologists

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Mendel made several significant contributions to the world of genetics. The first was his discovery of the recessive and dominant traits of "heritable traits" or genes, as we now call them. He found, by breeding pea plants, that certain genes were dominant over others, and that the characteristics of the dominant gene would take effect over the characteristics of the recessive gene. Another one of his discoveries is the Law of Segregation that states that of a pair of characteristics (e.g. blue and brown eye colour) only one can be represented in a gamete. What he meant was that for any pair of characteristics there is only one gene in a gamete even though there are two genes in ordinary cells. If your eyes are blue, green or grey you have two alleles for blue eyes (bb), then your gametes must have a blue allele (b); if your eyes are brown you might have two brown allele (BB), then your gametes have one allele for brown (B) or you might have one allele of each kind (Bb), in which case you make two kinds of gametes some contain the brown allele (B) and some contain the blue allele (b). His second law says that for two characteristics the genes are inherited independently. If you had the genotype AaBb you would make four kinds of gametes: they would contain the combinations of either AB, Ab, aB or ab. Suppose one of your parents had the genotype AABB then you would have inherited AB from this parent. Suppose also that your other parent had the genotype aabb then you would have inherited ab from this parent. The combinations of AB and ab are parental types. Your genotype is AaBb and some of your children will inherit these parental types either AB or ab from you. However, it is also possible for some of your children to inherit new combinations called "re-combinants" from you. These are Ab and aB.

Alfred Hershey and Martha Chase were two American scientists who set out one day to discover where the genetic material of a bacterium was contained- in the protein...