Bio3400 Chapter 8 Chromosome Mutations
  1. Variations in chromosome number can arise from                 , in which chromosomes or chromatids fail to disjoin during          .

  2.           for anything other than the    chromosome is often fatal. In          monosomy, such as              syndrome, only a section of a chromosome is lost.

  3.          usually exhibits less severe effects than monosomy; many plants can be viable in this state.

  4. A trisomic cell shows irregular pairing during          : the 3 chromosomes may synapse to form a            .

  5. In humans, trisomy of chromosome 21 results in       syndrome, usually caused by nondisjunction of the           chromosome 21 during meiosis.

  6. Other examples of trisomy syndromes are Patau syndrome (trisomy     ) and Edwards syndrome (trisomy     ).

  7. Polyploidy (more than 2 haploid sets of chromosomes) occurs mostly in plants, and can be either                 or                 , and sometimes                .

  8. Amphidiploid plants can also be produced by          cell hybridization.

  9. Rearrangements of chromosome segments include            ,               ,             , and                 .

  10. A chromosome           (or a deficiency) can occur near one end (           deletion ) or from the interior of the chromosome (              deletion ).

    • A deletion in recessive mutants may exhibit                  in a heterozygote.

  11. A              is a repeated segment of DNA caused by          crossing over during meiosis or through a replication error prior to meiosis.

    • A duplicated gene may exhibit phenotypic variations in genes that exhibit               

  12. An            involves a rearrangement of the linear gene sequence and may arise from chromosomal          ; the inversion can be paracentric or pericentri .

  13.                is a movement of a chromosomal segment to a new location in the genome.
    • A             translocation involves the exchange between                chromosomes; its unusual synapsis can also produce inviable gametes.

    • A common human rearrangement is               translocation.

  14. Some chromosome sites are          and susceptible to breakage, causing disorders such as Fragile    syndrome, which is the most common form of inherited mental retardation.