| A | B |
|---|
| aneuploidy | one or more chromosomes are present in extra copies or are deficient in number |
| Barr body | dense object inside nuclear envelope in female mammalian cells |
| chromosome theory of inheritance | genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns |
| crossing over | reciprocal exchange of genetic material between nonsister chromatids during prophase I |
| cytologenetic map | Chart of a chromosome that locates genes with respect to chromosomal features |
| deletion | loss of a fragment through breakage |
| Down syndrome | presence of an extra chromosome 21 |
| Duchenne muscular dystrophy | sex-linked recessive allele disease; characterized by progressive weakening and a loss of muscle |
| duplication | fusion with a fragment from a homologous chromosome |
| genetic map | ordered list of genetic loci along a chromosome |
| genetic recombination | combine traits of the two parents |
| genomic imprinting | expression of an allele in offspring depends on whether the allele is inherited from the male or female parent |
| hemophilia | sex-linked recessive allele disease; characterized by excessive bleeding following injury |
| inversion | reverse orientation of a chromosomal fragment to the chromosome from which the fragment originated |
| linkage map | genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes |
| linked genes | Genes located close enough together on a chromosome to be usually inherited together |
| map unit | unit of measurement of the distance between genes |
| monosomic | only one copy of a particular chromosome |
| nondisjunction | both members of a pair of homologous chromosomes or both sister chromatids fail to move apart properly |
| parental type | offspring with a phenotype that matches one of the parental phenotypes |
| polyploidy | organism possesses more than two complete chromosome sets |
| recombinant | offspring whose phenotype differs from that of the parents |
| sex-linked gene | gene located on a sex chromosome |
| translocation | resulting from attachment of a chromosomal fragment to a nonhomologous chromosome |
| trisomic | three copies of a particular chromosome |
| wild type | individual with the normal (most common) phenotype |
