Term | Definition |
Sex Chromosome | One of the pair of chromosomes that determine the sex of an individual. |
Autosome | Any chromosome that is not a sex chromosome. |
Sex-linked Trait | A trait that is determined by a gene found on one of the sex chromosomes, such as the X chromosome or the Y chromosome in humans. |
Linked Gene | One of a pair of genes that tend to be inherited together. |
Chromosome Map | A diagram of gene positions on a chromosome. |
Map Unit | In chromosome mapping, an increment of 1 percent in the frequency of crossing-over. |
Germ-cell Mutation | Mutation that occurs in an organism's gametes. |
Somatic-cell Mutation | A mutation that occurs in a body cell. |
Lethal Mutation | A gene or chromosomal mutation that influences the development of an organism cannot survive. |
Deletion | The loss of a part of DNA from a chromosome. |
Inversion | A reversal in the order of the genes, or of a chromosome segment, within a chromosome. |
Translocation | The movement of a segment of DNA from one chromosome to another, which results in a change in the position of the segment; also the movement of soluble nutrients from one part of a plant to another. |
Nondisjunction | The failure of homologous chromosomes to separate during meiosis 1 or the failure of sister chromatids to separate during mitosis or meiosis 2. |
Point Mutation | A mutation in which only one nucleotide or nitrogenous base in a gene is changed. |
Substitution | A mutation in which a nucleotide or a codon in DNA is replaced with a different nucleotide. |
Frameshift Mutation | A mutation, such as the insertion or deletion of a nucleotide in a coding sequence, that results in the misreading of the code during translation because of a change in the reading frame. |
Insertion Mutation | A mutation in which one or more nucleotides are added to a gene. |