anthro test 2

anthro test 2 - Anthropology Test 2 • Interaction of...

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Unformatted text preview: Anthropology Test 2 • Interaction of mutation and natural selection. o Polymorphism : the situation in a species or population where there are 2 or more alleles of a gene, and atleast 2 of the alleles have a frequencies greater than or equal to 1 percent. The mutation rate for any gene is very low, so it cannot get an allele up to 1%, so something else has to be acting on the allele to reach the threshold of 1%. Polymorphism is explained by natural selection acting on mutations. In our species, approximately 28% of our genes are polymorphic. Lets say there are 50,000 genes in our genome and 28% are polymorphic. This means there are approximately 14,000 polymorphic genes. Genetic variability allows a species to go through natural selection and adapt. Example: A,B,O blood system: The genotypes are AA, A0, AB, BB, BO, and OO, and these produced proteins. The proteins that can be produced are A,A, A and B, B, B, and none for the OO. If you are a type A blood at birth, you have the anti-B antibody. This means it produces antibodies against the B protein. If you are type AB blood, you produce no antibodies. If you are type B blood, you produce antibodies against the A protein. If you are type OO blood, you produce antibodies against both A and B proteins. o Balanced Polymorphism : situation where there are 2 or more alleles of a gene in a population or species, and at least 2 of the alleles have frequencies equal to or greater than 1%, and the polymorphism is due to heterozygotes having a higher fitness (natural selective advantage) than both homozygotes. Example: Red blood cell variants and Malaria: • Sickle Cell Allele o What is sickle cell ? Hemoglobin binds oxygen, and it is a protein that is comprised of 2 alpha and 2 beta polypeptide chains. Each alpha polypeptide chain has 141 amino acids, and each beta chain has 146 amino acids. Sickle cell is a result of a single point mutation affecting 1 amino acid. o Despite the expected intense natural selection against the sickle cell allele, the allele is maintained in high frequencies at polymorphic levels from 5-15% in some population. • Malaria : o Malaria is caused by a parasite, which is transmitted from an infected individual to an unaffected individual by a mosquito. When it gets into your system, it gets into the red blood cells. • Relationship between Sickle Cell Allele and Malaria o Evidence Geographical correlation between the distributions of polymorphic...
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anthro test 2 - Anthropology Test 2 • Interaction of...

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