UMass Amherst BIOLOGY 283 - Genetics Exam 3 Review (18 pages)

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Genetics Exam 3 Review



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Genetics Exam 3 Review

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Pages:
18
School:
University of Massachusetts Amherst
Course:
Biology 283 - General Genetics
General Genetics Documents

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Genetics Exam 3 Review Ch 8 Centromeric locations on chromosomes P Short arm Q Long arm Metacentric Perfectly centered Submetacentric Slightly off center Acrocentric Q 2x longer than P Telocentric Centromere on top only see Q arm Alterations of chromosome structure 1 The total amount of genetic infor in the chromosome can change a Deficiencies Selections b Duplications 2 The genetic material remains the same but is rearranged a Inversions b Translocations Deficiencies When they have a phenotypic effect usually detrimental Terminal deletion Edge of chromosome is lost single break Interstitial deletion two breaks and reattachment of outer pieces Ex Cri du chat 46 5pDuplications Repetitive sequences can cause misalignment between homologous chromosomes if crossing over occurs nonallelic homologous recombination results Usually don t cause harmful syndromes Duplicated genes can be passed on through families and evolve to have similar but distinct functions Gene family Orthologs Same gene in different species Paralogs Different versions of same gene in same species caused by duplications Both of homologs Copy Number variation Small but significant DNA varies in copy number among members of same species Common 1 10 of genome 1 Schizophrenia 2 Autism 3 Susceptibility to infectious disease 4 Cancer Red Green color Vision May have multiple copies due to mispairing and unequal crossing over makes color blindness more likely Inversions Segment that has been flipped into the opposite orientation 1 Pericentric inversion Centromere lies within inverted region 2 Paracentric inversion Centromere lies outsides inverted region Usually has no effect because all the genes are still there Translocation One segment of one chromosome becomes attached to another Caused by chromosomal breakage and DNA repair or Abnormal Crossovers 1 Reciprocal translocations Two nonhomologous chromosomes exchange genetic material 2 Unbalanced translocations Simple Exchange only occurs in one direction cause



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