A171Lecture2 - Lecture 2: How does variation and speciation...

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Lecture 2: How does variation and speciation into radiations occur? Genotype and phenotype: where does the variation come from? Topics to cover: What people look (behave?) like: the blueprint at conception (genotype) versus what happens during growth (phenotype). What does evolution act on? Genotype: DNA - blueprint to develop whole organism. Phenotype: what it looks like: heat determines sex, size and food, sex maturity and age / weight, environmental effects. Evolution = inherited change = change in genes in a population, but acting on phenotypes which are a poor expression of the genotype. DNA – deoxyribonucleic acid – enormous molecule. Double helix or twisted ladder where rungs are bases: Adenine, Thymine, Guanine, Cytosine. These pair: G with C and A with T. Three bases = one amino acid (makes proteins), one amino acid can be coded for by more than one sequence. Some code for stops and starts. Because of pairing, can unzip and make an identical copy, or a messenger RNA (ribonucleic acid) strand, which can start protein synthesis.
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Genes: DNA sequences that code for something like a protein to make something like hemoglobin or regulatory genes. Locus: position on a chromosome Alleles (allele): different forms of gene at a locus (ABO blood system). Can be 1 to many alleles. A and a or A1 A2 A3 etc…. Chromosomes come in matched pairs, so each person has two alleles of each gene (same or different). see http://www.bbc.co.uk/science/genes/who_am_i/inheriting_genes/life_is_a_lottery.shtml ) Homozygous = same allele (AA or aa) Heterozygous = different allele (Aa) Dominant and recessive alleles (co-dominant) Polymorphic: a trait that has more than two or more alleles with frequency of greater than 0.01 (arbitrary) so that: o Locus with A at 0.999 and a at 0.001 is not polymorphic but A at 0.8 and a at 0.2 is polymorphic. o
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This note was uploaded on 10/24/2009 for the course ANTH 171 taught by Professor Franciswhite during the Spring '09 term at University of Oregon.

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A171Lecture2 - Lecture 2: How does variation and speciation...

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