D3.7 Evidence for evol part III

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D3.7 Evidence for evol part III. jackie. Biochemical evidence provided by the universality of DNA and protein structures for the common ancestry of living organisms. - PowerPoint PPT Presentation

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  • D3.7 Evidence for evol part IIIjackie

  • Biochemical evidence provided by the universality of DNA and protein structures for the common ancestry of living organisms. DNA structure is universal, i.e., the same in all organisms, composed of polymers of the same four nucleotides: adenine, guanine, cytosine, and thymine Protein structure is universal, composed of polymers made of the same 20 amino acids Genetic code is universal: The genetic code whereby DNA is transcribed into RNA and then translated into proteins is universal, so that all organisms use the same codons for determining amino acid sequence

  • Biochemical evidence provided by the universality of DNA and protein structures for the common ancestry of living organisms.Summary: because all of the basic biochemistry of genetic information and protein synthesis is identical in all organisms, they likely inherited it from a common ancestry

  • How variations in specific molecules can indicate phylogeny. Globins: hemoglobin and myoglobin globin genes are present in all animals and some plants the greater the similarity in the globin genes of two species, the less time has passed during which mutations could accumulate, and thus, the degree of similarity can be used as a measure of how closely related the two species are the greater the similarity in a protein produced by two species, the more recently they shared a common ancestor the greater the difference in a protein produced by two species, the more distantly they shared a common ancestor

  • How variations in specific molecules can indicate phylogeny.For example, the hemoglobin of gorillas only differs by one amino acid from human hemoglobin whereas elephant hemoglobin differs from human hemoglobin by 26 amino acids. Therefore elephants separated as a species from a common ancestor with humans longer ago then did gorillas. Information like this can help to group organisms in trees of descent and suggest how long ago they had a common gene pool

  • How biochemical variations can be used as an evolutionary clock Hemoglobin varies between vertebrates: Hemoglobin, a blood protein found in all vertebrates, shows amino acid differences compared to humans in of a variety of vertebrates: horse: 18 mouse: 16 reptile: 35 frog: 62 shark: 79 Calibrate variation to time: Hemoglobin amino acid differences correlate to geological time based on fossil record: mammals: originated 70 million years ago reptile: originated 270 million years ago frog: originated 350 million years ago shark: originated 450 million years ago

  • How biochemical variations can be used as an evolutionary clockEstablish a variety of molecular clocks: Hemoglobin changes at a regular rate over hundreds of millions of years, acting as a molecular clock. A variety of proteins have been studied, each producing its own molecular clock. Histones (organize DNA) hardly change at all. Cytochrome c (a mitochondrial protein) changes slowly. Hemoglobin (blood protein) changes moderately. Fibrinopeptides (clotting proteins) change rapidly

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