1 universal features of life on earth

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PowerPoint for BI 520-01 …

PowerPoint for BI 520-01
Spring 2013

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  • 1. Lecture 1 What is it to be alive? ©
  • 2. Lecture 1
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  • 4. Chapter 1
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  • 7. Lecture 1 Prokaryotic Gene Promoter Protein Coding Sequence Terminator Intron ~20 bp Eukaryotic Gene Exon 1 Exon 2 Exon 3 Promoter Intron ~2kb Intron>5kb Intron~5kb
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  • 10. So, who’s wrong? Both!
  • 11. Lecture 1One of the most profound technologicalaccomplishments in human history is the sequencing of the human genome…
  • 12. Lecture 1One of the major differences between prokaryotes and eukaryotes in the size/complexity of their genomes.
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  • 15. Mutation – a change in the nucleotide sequence of the geneticmaterial of an organism – is the underlying force of evolution. •Mistakes during replication •Chemical Changes in the nucleic acids •UV – dimerization •Spontaneous decomposition – base changes •Chemical/physical changes at the chromosome level •Radiation (X-ray/Gamma) – double-strand breaks •Sexual reproduction (polyploidy)
  • 16. Lecture 1 More than 200gene families arecommon to all life. Most of these “orthologous genes” are essential.
  • 17. Lecture 1But how do they do this whenmost mutations tend to mess things up more than they improve them?
  • 18. They must find a way to break free from the oppression of natural selection
  • 19. Lecture 1Duplication events Retroviruses Horizontal Gene Transfer - genes can be transferred between organisms both in the laboratory, and in nature.
  • 20. hCYP3A Locus Chromosome-7 ~80% Homology 40 Kb 4 Kb 5 Kb P2 P1 3A43 3A4 3A7 3A5 43cDNA 4cDNA 7cDNA 5cDNA All have roughly 90% homology in the first 1000 bp of their promoters.Finta & Zaphiropoulos, 2000 Gellner et al., 2001
  • 21. Irreducible complexity
  • 22. Lecture 1Eukaryotes often have pseudogenes,duplicated genes that have accruedmutations that render them inactive, intheir genomes. Mutated regulatory elements, frame shifts, addition/loss of stop codons, lost splice sites, deleterious mutations, etc.
  • 23. Lecture 1
  • 24. Conoidea based on 12S Ribosomal RNA
  • 25. Lecture 1We make assumptions when we do this… •Evolution is real - members of a group share a common evolutionary history, and are "closely related," more so to members of the same group than to other organisms. •Bifurcation - new kinds of organisms may arise when existing species or populations divide into exactly two groups. •Organisms change over time – closely-related groups are share synapomorphies, unique features not present in more distant ancestorsAnd even more when we use gene sequences… •Mutations are a “one-way” street •We can assign a “value” for every base-pair mutated •“horizontal gene transfer” has not occurred among the orthologues.
  • 26. Lecture 1 The identification and characterization of gene orthologues helps us in ever expanding ways:1. Enhanced discovery • By finding regions that are highly conserved, primers can be designed to discover orthologues from new species2. Accelerated science • We can compare gene sequences and hint at their function, expression patterns, etc.3. More powerful experiments • We can plan methods to genetically engineer just about anything4. GAAATAACA and Pharmacogenomics • We can peer into our own genomes and predict certain diseases and the success of many treatments