Molecular Text 4.9

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  1. ·         The role of DNA duplication in evolution is not confined to the __, but can also act on a smaller scale to create __ by stringing together short duplicated segments of DNA
    o   The proteins encoded by genes generated in this way can be recognized by the presence of repeating similar __ which are covalently linked to one another in series
    • expansion of gene families
    • single genes
    • protein domains,
  2. ·         In genes that have evolved in this way, as well as in many other gene, , each __ often encodes an __, or domain
    ·         The organization of DNA coding sequences as a series of __ has greatly facilitated the evolution of new proteins
    • separate exon
    • individual protein folding unit
    • such exons separated by long introns
  3. o   The duplications necessary to form a __, for example, can often occur by __ anywhere in the __ on either side of an exon: without __there would be only a few sites in the original gene at which a __ could duplicate the domain
    §  By enabling the duplication to occur by __at many potential sites rather than just a few, introns do what?
    • single gene coding for a protein with repeating domains
    • breaking and rejoining the DNA
    • long introns
    • introns 
    • recombinational exchange between DNA molecule 
    • recombination 
    • increase the probability of a favorable duplication event
  4. ·         More generally, we know from genome sequences that the various parts of gene—both their __ and __—have served as __ that have been duplicated and moved about the genome to create the great diversity of living things
    • individual exons and their regulatory elements
    • modular elements
  5. ·         The __ differences of distantly related organisms overshadow __ variation even more dramatically
    o   Each fixed difference between the human and the chimp started out as a __ in a single individual
    • inter-species
    • intra-species
    • new mutation
  6. ·         If the mutation is deleterious, its eliminated by __. If it is advantageous, its inherited
    ·        There are __ that can be fixed, but less rapidly, about 1/2N, N being the population
    purifying selection

    neutral mutations
  7. ·         One important source of variation is the presence of many __ of large blocks of DNA. A human should have roughly 100 differences involving long sequence blocks
    o   Some of these “__” will be common, while others are not
    §  Nearly half will contain known gene
    • duplications and deletions
    • copy number variations
  8. ·         The __ that have been most extensively characterized are __

    o   These are what?
    • intra-species variations
    • single-nucleotide polymorphisms (SNPs)
    • simply points in the genome sequence where one large fraction of the human population has one nucleotide, while another substantial fraction has another
  9. ·         Mapped sites in the human genome that are __(meaning there is a reasonable probability that the genomes of two individuals will differ at that site) are useful
Card Set:
Molecular Text 4.9
2015-01-25 22:40:26
Test One
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