click below
click below
Normal Size Small Size show me how
Chapter 12 Vocabbbb
| 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 in such a way that the 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 seperate during meiosis 1 or the failure of sister chromotids to seperate 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 in replaced with a different nucleotide |
| frameshift mutation | a mutation, such as the insertion or deletion of a nucleotide in a coding seuqence, 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 |
| pedigree | a diagram that shows the occurence of a genetic trait in several generations of a family |
| carrier | in genetics, an individual who has one copy of a recessive autosomal allele that causes disease in the homozygous condition |
| genetic disorder | an inherited disease or disorder that is caused by a mutation in a gene or by a chromosomal defect |
| polygenic | describes a characteristic that is influenced by many genes |
| complex character | a character such as skin color that is influenced strongly by both genes and the environment |
| multiple alleles | more than two alleles (versions of a gene) for a genetic trait |
| codominance | a condition in which both alleles for a gene are fully expressed |
| incomplete dominance | a condition in which a trait in an individual is intermediate between the phenotype of the individual's two parents because the dominant allele is unable to express itself fully |
| sex-influenced trait | an autosomal trait that is influenced by the presence of male or female sex horemones |
| Huntington's disease | a rare hereditary disease of the brain characterized by involuntary movement of the limbs or face, decreasing mental abilities, and eventual death |
| amniocentesis | a procedure used in fetal diagnosis in which amniotic fluid is removed from the uterus of the pregnent woman |
| chorionic villli sampling | a procedure in which the chorionic villi to are analyzed to diagnose fetal genotypes |
| genetic counseling | the process of testing and information potential parents about their genetic makeup and the likelihood that they will have offspring with genetic defects or hereditary diseases |
| gene therapy | a technique that places a gene into a cell to correct a hereditary disease or to improve the genome |