Genetics second test

  1. Multigene Trait
    more than 1 gene specifying a given phenotype
  2. Pleiotrophy
    the production by one particular mutant gene, of apparently unrelated multiple effects at the phenotopic level
  3. Complete Dominance
    Aa = AA
  4. Incomplete (semi-) dominance
  5. Co-Dominance
    • •alleles
    • not mutually related in terms of dominance-recessivity.

    • Instead, their gene products occur
    • independently, and both are manifest phenotypically.
  6. Penetrance
    • The frequency (in percent) with which a (dominant or homozygous recessive) gene or gene combination manifests itself in the phenotype of the carriers.
    • It is complete when:
    • homozygous recessives show one phenotype.
    • homozygous dominants show another phenotype.
    • All the heterozygotes are alike.
  7. Expressivity
    the degree of expression of a gene or mutation
  8. Epistasis
    a form of gene interaction whereby one gene (A) interferes with the phenotypic expression of another non allelic gene (B).
  9. Complementation
    the production of a wild-type phenotype when two haploid genomes bearing different recessive mutations are united in the same cell.
  10. Complementation analysis
    Determination of whether cells with the same phenotype have the same genotype.
  11. Complementation group
    the members of such a group fail to complement one another, and they functionally define a “gene”
  12. conditional mutant
    • a mutant whose viability is dependent on a set of (permissive) conditions
    • ex: auxotrophs, temperature-sensitive
  13. pedigree
    a list of ancestry or genealogical register
  14. autosomal dominant
    females and males are equally likely to be affected

    on average, half the individuals in sibships with an affected parent are affected
  15. Centromere
    the region of each chromosome with which the spindle fibers become associated during mitosis and meiosis
  16. Karyotype
    the particular chromosome complement of an individual or of a related group of individuals, defined both by the number and morphology of the chromosomes
  17. Aneuploidy
    having one or more whole chromosomes or chromosome segments absent form or in addition to the basic chromosome complement
  18. polyploids
    contain three or more chromosome sets
  19. Are polyploids euploid?
  20. Autopolyploid
    >2 monoploid chromosomes sets
  21. Causes of genome duplication
    • Meiotic non-reduction of gametes
    • and
    • genome duplication w/o cytokinesis (after fertilization)
  22. autopolyploids
    fertility disturbances due to unbalanced meiosis (specially in odd-numbered autopolyploids)
  23. allopolyploids
    • contain structurally and genetically different chromosome sets
    • allopolyploidy arises from hybridization, plus genome duplication
  24. monoploids
    a single chromosome set that is repeated in polyploids
  25. haploid
    the chromosome complement of the gametes of a species
  26. Deletions
    • chromosomal segments are missing
    • even small deletions are homozygous lethal
    • large ones are even heterozygous lethal
    • deletion of a locus uncovers a recessive mutation when they pair with a "full-length" chromosome carrying the recessive allele at the locus
  27. duplication
    a chromosomal structural change resulting in the doubling of a section of the genome
  28. intra=chromosomal duplications
    • the duplicated segments are contained within a single chromosome
    • tandem (contiguous) duplications
    • non-contiguous duplications
  29. inter-chromosomal duplications
    the duplicated segment is incorporated into a non-homologous chromosome
  30. paracentric inversion
    does not include the centromere
  31. pericentric inversion
    includes the centromere
  32. chromosome translocation
    • change in the position of chromosome segments within the chromosome complement
    • it can be intra-chromosomal.... but it usually involves intergchange of parts between non-homologous chromosomes
  33. reciprocal translocation
    • (symmetrical)
    • asymmetrical
  34. non reciprocal translocation
  35. terminal translocations (at the telomere are not possible)
  36. Robertsonian translocations
    non-homologous chromosome fusion at their centromeres
  37. compound chromosomes
    any monocentric chromosome in which the material from one chromosome arm is represented twice
  38. acrocentric
    • two arms may join
    • by attachement of the base of one to the terminus of there other to form
  39. metacentic
    by attachment of both proximally to a single centromere.
  40. the ends of compound chromosomes may join to form a ring chromosome
  41. heterozygous symmetrical reciprocal translocations
    • the four chromosomes share partial homology, but no two are identical
    • they are characterized by a cross configuration of the paired chromosomes in meiosis
    • they cause semi sterility
  42. Adjacent segregation
    segregation of a heterozygous reciprocal translocation in which a translocated chromosome and a normal chromosome, segregate together, producing an aneuploid gamete.
  43. adjacent 1
    homologous centromeres go to opposite poles (they disjoin as usual)
  44. adjacent 2
    homologous centromeres go to the same pole (non disjuction)
  45. alterate segreagation
    • neighboring chromosomes will not go to the same pole
    • all the gametes are euploid and half are carriers for the translocation
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Genetics second test
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