Class notes exam 3

Class notes exam 3 - Class Notes Mutations in germ line or...

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Class Notes 10/5/07 Mutations in germ line or somatic cells may give different consequences Five main types of genetic changes contribute to evolution Genome alterations are caused by failure of the normal mechanisms for copying ad maintaining DNA One in 10^10 bases can carry a point mutation – human Bacterial mutation rate: 20 min. generation time In a culture, it can contain millions of mutated cells. Various mutations make the cells fit to a certain condition such as poison and nutrients. Mutations give them advantages to live in a condition – use these mutants for selection markers for genetics experiments In human – 1 in 100,000 births have noticeable defects - .1 nucleotide change / 10^9 haploid genome Point mutations – nonsense mutations, missense mutation, silence mutations (accumulated) – base pair change Ex: the DNA sequence of one gene in mouse is different from that of the same gene in human but protein sequences are identical Gene duplication – generation of new genes One pair becomes two pairs: the other pair undergoes free changes Bacillus gene: figure 9-4 Collagens, opsins, globins: result of gene duplications Errors in homologous recombination The evolution of globin genes Globin gene family – originated from a common ancestor
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Bacteria – a hemoglobin related gene Primitive single chain oxygen carrying globin Branched in to alpha and beta about 500 million years ago Beta chain underwent a duplication, fetal beta globin emerges New genes underwent further modifications by point mutations – globin cluster in chromosomes Exon Shuffling Duplication of exons Repeating the same exons: origin
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Class notes exam 3 - Class Notes Mutations in germ line or...

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