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26 Cards in this Set
- Front
- Back
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What are transposable elements?
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Mobile segments of genetic material present in all euk. Nonrandomly distributed thoughout genome. Makes up 1/3 of human genome (repetitive seq). Causes insertional mutagenesis
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What are the types of transposable elements?
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Retrotransposons (class I): DNA to RNA, use reverse transcriptase to make a DNA copy of the RNA to insert. Class II: only DNA that moves. Class III: mini inverted-repeats (MITE)
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What are the consequences of transposable elements?
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Antibody diversity, susceptibility to radiation & mutatgens, cancer, aging, & origin of perpetuated disorders
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What is anticipation?
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The apparent worsening of a disprder w/ subsequent generations
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What are the charac of fragile X syndrome?
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X-linked mental retardation, autisum, thin, elongated face, hypotonia, joint laxity, macro-orchidism. Demonstrates anticipation.
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What causes fragile X?
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Trinucleiotide repeat (CGG) in 5' untranslated region of FMR-1 gene. Enlargement blocks transcription
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What is myotonic dystrophy?
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Autosomal dominant multi-system disorder charac by myotonia, weakness in face & distal limbs, cataracts, frontal baldness, multi endocrinopathies
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What causes myotonic distrophy?
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Trinucleotide repeats (CTG) in 3' untranslated region. Repeat is transcribed-> protein kinase. Repeat enlarges w/ maternal & paternal transmission
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Where are possible locations of trinucleotide repeats?
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5' untranslated (fragile X), 3' untranslated (myotonic dystrophy), w/i open reading frame; exons (neurodegenerative disorders), w/I intron (Friiedreich ataxia-GAA repeat)
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What are the 2 types of trinucleotide repeat disorders?
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Type 1: glutamine, small CAG repeats, neurodegen disorders. Type 2: CGG or CTG repeats, large repeats, multisystem disorders
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How do repeats cause disease?
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Loss of fcn (disrupt transcription, translation, due to methylation). Gain of fcn (excess metabolite inhibits enzyme). Dominant neg effect (abnormal product interferes w/ normal physiologic fcn of product
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What is epigenetics?
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The transmission of info from a cell or multicell organism to its descendents w/o that info being encoded in the nucleotide seq of the genes
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What causes epigenetic inheritance?
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The result of changed gene expression & may be reversible.May be somatically inherited, but it is not transmittedthrough meiosis
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What are some examples of epigenetic mechs?
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X-activation, imprinting, DNAmethylation, histone modification, chromatin modification, & RNA=assoc silencing
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Describe histome acetylation.
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Post-translation mod of epsilon group of lysine catalyzed by HATs-> neutralizes the + charge & creates amore open DNA structure
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Describe chromatin remodeling.
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The physical act of moving DNA relative to the histone octamer. ATP-dependent exist w/i nuc
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Describe RNA silencing.
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Co-suppression; A novel genome reg system that will limit the RNA transcript level by activating a seq-specific RNA degradation process
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What is epigenetic therapy?
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Agents that alter DNA methylation patterns or histones
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What are modifier genes?
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Genes that have small quantitative effects on the level of expression of another gene
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What are the clinical features of Huntington's disease?
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Chorea, premature selective cell death of basal ganglia. Late onset produces reproductive dilemmas
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What causes Huntington's disease?
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trinucleotide repeat (CAG) on 4p16.3 w/I coding seq. Age onset correlates w/ size of repeat
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What is Van derWoude syndrome?
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The 1st example of the a gene mapped through linkage analysis that modifies the expression of a major gene. @ Chrom 1p13. Risk is inc by gene @ 17p11.2-p11.1
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What is Jevell & Lange-Nielson syndrome?
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AR disease. Profund congenital deafness,syncopal attacks & sudden death due to prolong QT.High prevalence in Norway
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What causes Jevell & Lange-Nielson syndrome?
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A mutation in 1 of 2 genes that assemble a K channel (KCNQ1, KCNE1)-> disrupts endolymph production in the stia vascularis
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What is Beckwith-Wiedemann syndrom?
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Growth disorder charac by macrosomnia, macroglossia, visceromegaly, embryonal tumors, omphalocele, neonatal hypoglycemia, earlobe crease, & post helical pits
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What is the etiology of Beckwith-Weifmann syndrome?
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Imprinting: abnormal methylation of *LIT1 (Normally methylated maternal chrom & unmethylated paternal chrom). Or H19 (paternal is normally methylated)
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