Natural selection - Natural selection Many conditions which...

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Natural selection Many conditions which we recognise as genetic diseases are actually present in certain populations because, either presently or in the not too far distant past, they actually conferred a survival advantage on their carriers. In most cases the disease is manifested in the homozygote whereas the heterozygote is at an advantage. Malaria has been a powerful selective force. In countries where malaria is endemic are found high frequencies of many such mutations, for example the sickle cell mutation in the beta globin gene, the thalassemia mutations affecting either alpha or beta globin genes and favism (glucose-6-phosphate dehydrogenase deficiency). How are genetic diseases maintained in populations? In the case of a dominant and a recessive allele at a locus, it is not immediately obvious what will happen to their frequencies in the population as generations go by. Do we expect the recessive allele to diminish in frequency? Also, there will be three genotypes, homozygotes for each of the alleles and the heterozygotes. What will be
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This note was uploaded on 11/22/2011 for the course CHEMISTRY CHM1025 taught by Professor Laurachoudry during the Fall '10 term at Broward College.

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Natural selection - Natural selection Many conditions which...

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