Biology- Ch. 12 Inheritance Patterns and Human Genetics
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31 terms
Terms | Definitions |
|---|---|
 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 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 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 separate during meiosis I or the failure of sister chromatids to separate during during mitosis or meiosis II. |
| 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. |
| pedigree | a diagram that shows the occurrence 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 allele | more than two alleles (versions of the 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 dominate allele is unable to express itself fully. |
| sex-influenced trait | an autosomal trait that is influenced by the presence of male or female sex hormones. |
| Huntington's disease | a rare hereditary disease of the the brain characterized by involuntary movements of the limbs or face, decreasing mental abilities and eventual death. |
| amniocentisis | a procedure used in fetal diagnosis in which amniotic fluid is removed from the uterus of the pregnant woman. |
| chorionic villi sampling | a procedure in which the chorionic villi to are analyzed to diagnose fetal genotypes. |
| genetic counseling | the process of testing and informing 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 hereditary disease or to improve the genome. |
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