Meeting 19

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  1. SCID
    diseae caused by mutation in single gene (IL2Rc gene)-gene makes sure differentiation of white blood cells happen correctly-when the gene is mutated, that cell can’t make cell lineges in differentiated form = immunodeficiency-example of a gene where gene therapy works-take the gene, put into retroviral vector, infect stem cells with virus, and then inject stem cells in blood ---- stem cells go on to create proper lineages-b/c it’s a retroviral vector gene is inserted into genome – in some cases this can cause cancer (inserted into region you don’t want to disrupt: causes over-proliferation and subsequently leukemia
  2. gene therapy is a form of:
    • reverse genetics
    • -reverse: known protein/gene causing disease, insert 'fixed copy' back into organism is gene therapy; taking a gene in a testube and going back to the test tube

    • forward: mutagenizing organisms, seeing how they affect organism
    • CANNOT do forward genetics in hhumans (Can't mutagenize, can't force them to mate with anyone)
  3. mendelian disease
    single gene is the genetic bases of the disease
  4. autosomal dominant
    when one bad copy of a gene located in an autosome (one of the 22 human chromosomes that aren't sex chromosomes) is DOMINANT and therefore expressed in a heterozygote (ex. huntington’s); usually one parent has the disease (symptoms don't manifest until after reproductive age)
  5. the x-linked recessive
    recesi=sive allele on the x-chromosome will mostly be expressed in males; mothers are phenotypically normal and act as carriers; need two bad copies on the x-chromosome
  6. autosomal recessive
    both parents must be heterozygous carriers of the allele in order for their children to be at risk for the disease; needs both copies of the recessive allele from each parent (ex. cystic fibrosis)
  7. Image Upload 1
    autosomal dominant
  8. Image Upload 2
    autosomal recessive
  9. x-linked recessive
    Image Upload 3
  10. number of carriers is always larger than the number of people who actually have the disease:
    carrier versus incidence frequency
  11. founder effect
    small population that either increases or stays the same and has a basis of this defect: the members of this population share these bad genes = increased risk of genetic disease (all of us have bad genes)
  12. first study of dNA
    Nicher; collected WBC's within used/collected bandages
  13. resucue analysis is essentially:
    gene therapy; rescue analysis only comes later when you know what gene you're talking about
  14. in a heterozygote:
    you'd see two bands on the gel; in someone who's HOMOZYGOUS, you'd only see one band because they have two copies of the same gene
  15. RFLP (restriction fragment length polymorphism)
    differences among individuals in the sequence of genomic DNA that create or destroy sites recognized by particular restriction enzymes; are one of several types of sequence differences between individuals that can serve as DNA-based molecular markers in human linkage studies
  16. Image Upload 4
    see how A cuts two different lengths? that shows up on a gel, because of the RFLP; this can be a phenotype just like CyO can be or whatever; here you're just tracking a molecule; B (there's no RFLP), so the bands are the same size and just come out as the same length on the gel
  17. SNP (single nucleotide polymorphism)
    some place in the genome where you might have one letter or a different one; RFLP's can be SNPs but not always (for example if there was a deletion not replacement)

    LOT'S of SNPs aren't RFLPs

    can test for these using: can sequence it (PCR) around that position and then sequence the DNA; need to know the sequence in general to find the surrounding area (that will hopefully stay the same, can be used to make the probes)

    also microarray: big enough it's unique, but not too big that it overwhelms the discrepancy; if you get the temperature just right, there will only be hybridization with the one that matches EXACTLY; the others will not hybridize
  18. SSRs (simple sequence repeats)
    some different number of repeats of some small sequence; mutates rapidly because the polymerase tends to slip

    to test: PCR...then run a gel, primers that are out here, you'll get something shorter or longer depending on the number of repeats there are
  19. simple-sequence DNA
    short, tandemly repeated sequences that are found at centromeres and telomeres as well as at other chromosomal locations and are not transcribed; also called satellite DNA??
  20. BAC
    bacterial artificial chromosome; big plasmid
  21. genetic maps
    places where the markers are; knowing there can be differences in individuals between markers
  22. BRCA1 and BRCA2
    autosomal dominant mutation; when looking at families, you find markers that are associated with people who have the disease
  23. genetic heterogeneity
    mutations in any one of multiple different genes can cause the same disease
  24. polygenic traits
    alleles of multiple genes, acting together within an individual contribute to both the occurence and the severity of disease
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Meeting 19
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