Presentation19.5

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Presentation19.5

  1. 1. DUPLICATIONS,REARRANGEMENTS, ANDMUTATIONS OF DNA CONTRIBUTETO GENOME EVOLUTION!Namroo AnnapareddyWill ChenEsther Park
  2. 2. Overview The basis of change at the genomic level is mutation  Which underlies much of genome evolution The earliest from of life likely had a minimal number of genes, including those necessary for survival and reproduction. The size of genomes has increased over evolutionary time, with the extra genetic material providing raw material for gene diversification.
  3. 3. Duplication of Chromosome Set Errors in Meiosis. Polyploidy : One or more extra sets of chromosomes. This can cause new species and occurs often in plant Mutations move on if the organism reproduces.
  4. 4. Duplication and Divergence of DNA segments Errors in meiosis can lead to duplication of genes. The transposable elementsprovide sites where nonsisterchromatids can cross over. Slippage can occur duringDNA replication and cancause a region to not be deletedor copied twice.
  5. 5. The Human Globin Genes Duplication events can lead to the evolution of genes with related functions. Comparison of gene sequences in multigame family suggest the order. All evolved from the same gene. After duplication arose mutations.
  6. 6. Evolution of Genes with Novel Functions One copy of a duplicated gene can undergo alterations that lead to a new function for protein product.
  7. 7. Rearrangements of Parts of Genes: ExonDuplication and Exon Shuffling A exon within a gene could be duplicated on one of the homologous chromosomes but deleted on the other. The gene with the duplicated exon would code for a second protein containing the encoded domain and cause a structural change. Exon shuffling.
  8. 8. Example of Exon Shuffling An example would be TPA protein that is used for blood clotting. It has 4 domains and can hold three types. One exon would be duplicated to fill the forth domain.The three types are EGF ( Epidermal Growth Factor), Fibronectin gene, and Plasminogen gene. The order they shuffle is unknown.
  9. 9. Exon Shuffling EGF EGF EGF EGF Epidermal growth factor gene with multiple EGF exons (green) Exon Exon shuffling duplication F F F F Fibronectin gene with multiple “finger” exons (orange) F EGF K K K Plasminogen gene with a Exon shuffling “kringle” exon (blue) Portions of ancestral genes TPA gene as it exists todayFigure 19.20
  10. 10. How Transposable Elements Contribute toGenome Evolution The transposable elements can contribute to the evolution of the genome. The presence of homologous transposable elements sequences scattered throughout the genome allow recombination. The movement of transposable elements around the genome can have several direct consequences. Transposable elements can lead to new coding sequences. Over long periods of time, the generation of genetic diversity provides more raw material for natural selection to work on during evolution.

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