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| Chromosome Theory | A basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns |
| Wild Type | An individual with the normal (most common) phenotype |
| Mutant Phenotype | Traits that are alternatives to the wild type. Different phenotype. Caused by changes or mutations the wild type |
| Sex-Linked Genes | A gene located on a sex chromosome |
| Linked Genes | Genes located close enough together on a chromosome to usually be inheirited together |
| Genetic Recombination | General term for the production of offspring that combine the traits of the two parents |
| Parental Type | An offspring with a phenotype that matches of the parental phenotypes |
| Recombinants | An offspring whose phenotype differs from that of the parents; also called recombinant type |
| Linkage Map | A genetic map based on th frequencies of recombination between markers during crossing over of homologous chromosomes |
| Cytological Map | Chart of chromosomes that locates genes with respect to chromosomal features |
| Duchenne Muscular Dystrophy | A human genetic disease caused by a sex-linked recessive allele; characterized by progresive weaking and a loss of muscle tissue |
| Hemophillia | A human genetic disease caused by a sex-linked recessuve allel; characterized by excessive bleeding following injury. |
| Barr body | a dense object along the inside of the nuclear envelope in female mammalian cells, representing an inactivated X chromosome |
| nondisjunction | an accident of meiosis or mitosis, in which both members of a pair of homologous chromosomes or both sister chromatids fail to move apart properly |
| trisomic | having three copies of a given chromosome in each body cell rather than two |
| polyploidy | a chromosomal alteration in which the organism possesses more than two complete chromosome sets |
| aneuploidy | a chromosomal aberration in which certain chromosomes are present in extra copies or are deficient in number |
| deletion | a deficiency in a chromosome resulting from the loss of a fragment though breakage, or a mutational loss of a nucleotide from a gene |
| duplication | an aberration in chromosome structure resulting from an error in meiosis or mutagens; duplication of a portion of a chromosome resulting from fusion with a fragment from a homologous chromosome |
| inversion | an aberration in chromosome structure resulting from an error in meiosis or from mutagens; reattachment in a reverse orientation of a chromosomal fragment to the chromosome from which the fragment originated |
| translocation | n aberration in chromosome structure resulting from an error in meiosis or from mutagens; attachment of a chromosomal fragment to a nonhomologous chromosome |
| Down syndrome | a human genetic disease resulting from having an extra chromosome 21, characterized by mental retardation and heart and respiratory defects |
| fragile-X syndrome | a hereditary mental disorder, partially explained by genomic imprinting and the addition of nucleotides to a triplet repeat near the end of an X chromosome |
