Term | Definition |
sex chromosomes | genes that determine the sex of an individual |
autosomes | chromosomes that do not determine the sex of a person |
sex-linked trait | a trait that is coded by an allele on a sex chromosome |
linked genes | a pair 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 one percent |
Germ-cell mutations | mutations in the gametes |
somatic-cell mutations | mutations in the body cells |
lethal mutations | cause death (usually before birth) |
deletion | the loss of a piece of chromosome due to breakage |
inversion | a chromosomal segment breaks off and flips around |
translocation | a piece of one chromosome breaks off and goes onto another |
nondisjunction | a chromosome does not separate during meiosis |
point mutation | substitution, addition, or removal of a single nucleotide |
substitution | one nucleotide replaces another |
frameshift mutation | an incorrect grouping of the remaining codons |
insertion mutations | one or more nucleotides are added to a gene |
pedigree | a diagram that shows how a trait is passed along through generations |
genetic disorders | diseases or disabling conditions that have a genetic basis |
carriers | people who have recessive genes but not the disease |
polygenic | characters that are influenced by several genes |
complex characters | characters influenced by elements and genes |
multiple alleles | genes with 3 or more alleles |
codominance | both alleles are dominant |
incomplete dominance | a trait that is intermediate between the parents |
sex-influenced traits | autosomal traits |
huntington's disease | an autosomal dominant condition characterized by forgetfulness and irritability |
amniocentesis | removing fluid from pregnant women to see genes/sex of baby |
chorionic villi sampling | doctor takes sample of chorionic villi cells to find genetic diseases |
genetic counseling | informing a person about their genetic makeup |
gene therapy | placing healthy genes into genes that are defective |