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Biology: Chapter 121
Chapter 12.1 Vocabulary
Term | Definition |
---|---|
Sex Chromosome | contains genes that determine the sex of an individual |
Autosome | the remaining chromosomes that are not directly involved in determining the sex of an individual |
Sex-Linked Trait | refers to a trait that is coded for by an allele on a sex chromosome |
Linked Gene | pairs of genes that tend to be inherited together |
Chromosome Map | a diagram that shows the linear order of genes on a chromosome |
Map Unit | a frequency of crossing-over of 1 percent |
Germ-Cell Mutation | a mutation, a change in the nucleotide-base sequence of a gene or DNA model, that occurs in an organism's gametes |
Somatic-Cell Mutation | a mutation that occurs in an organism's body cells and can therefore affect the organism |
Lethal Mutation | mutations that can cause death, often before birth |
Deletion | a loss of a piece of a chromosome due to breakage |
Inversion | when a chromosomal segment breaks off, slips around backward, and reattaches |
Translocation | when a piece of one chromosome breaks off and reattaches to a nonhomologous chromosome |
Nondisjunction | a chromosome fails to separate from its homologue during meiosis |
Point Mutation | a change that occurs within a single gene or other segment of DNA on a chromosome |
Substitution | when one nucleotide replaces another; the amino acid can be changed |
Frameshift Mutation | can result as a loss of a nucleotide; when all amino acids downstream from the lost nucleotide change |
Insertion Mutation | when one or more nucleotides are added to a gene, which can also result in a frameshift mutation |