genetics

• Aneuploidy


  An organism gains or loses one or more chromosomes and has other than an exact multiple of the haploid set
• Euploidy


  Complete haploid sets of chromosomes are present
• Monosomy


  Loss of single chromosome in diploid genome (2n-1 chromosomes)
• Trisomy


  Gain of single chromosome (2n +1 chromosomes)
• Nondisjunction


  Chromosomes or chromatids fail to disjoin and move to opposite poles during meiosis I or II
• Monosomies for autosomal chromosomes are usually not tolerated in humans or other animals</b>
• Monosomies are better tolerated in plants (less viable though)
• Trisomies often found in spontaneously aborted fetuses (20 percent of conceptions)
• Polyploidy


  More Than Two Haploid Sets of Chromosomes Are Present
• Autopolyploidy


  Addition of one or more sets of chromosomes identical to the haploid complement of the same species
• Allopolyploidy


  Combination of chromosome sets from different species as a consequence of interspecific matings
• Polyploidy is very common in plants but less common in animals
• Deletion


  When a chromosome breaks in one or more places and a portion of it is lost
• Cri Du Chat Syndrome


  • Deletion of small terminal part of chromosome 5
• Duplication


  A repeated segment of the genetic material
• Inversion


  Rearrangement of the linear gene sequence
• Reciprocal translocation


  Exchange of segments between two nonhomologous chromosomes
• Nonreciprocal translocation


  Rearrangement of genetic information
• Genetic information can be lost or gained through chromosomal rearrangements