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1.aneuploidy: a chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number.
2.barr body: a dense object lying along the inside of the nuclear envelope in female mammalian cells, representing an inactivated X chromosome.
3.chromosome theory of inheritance: generalization that genes are located on chromosomes and that the behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns
4.crossing over: process in which homologous chromosomes exchange portions of their chromatids during meiosis
5.cytogenetic maps: a chart of a chromosome that locates genes with respect to chromosomal features distinguishable in a microscope
6.deletion: change to a chromosome in which a fragment of the chromosome is removed
7.down syndrome: trisomy 21
8.duchenne muscular dystrophy: deleted dystrophin gene (X-linked recessive)
9.genetic map: an ordered list of the genetic loci along a particular chromosome
10.genetic recombination: the regrouping of genes in an offspring that results in a genetic makeup that is different from that of the parents
11.genomic imprinting: a phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent
12.haplo diploid system: there are no sex chromosomes in most species of bees and ants. Females develop from fertilized eggs (diploid) and males develop from unfertilized eggs (haploid)
13.hemophilia: an X-linked recessive disorder in which blood fails to clot properly, leading to excessive bleeding if injured.
14.inversion: (genetics) a kind of mutation in which the order of the genes in a section of a chromosome is reversed
15.linkage map: a genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes.
16.linked genes: genes located on the same chromosome that tend to be