| A | B |
|---|
| chromosomal theory of inheritance | The theory that chromosomes are linear sequences of genes. |
| wild type | The normal phenotype for a character (the most common in natural populations). |
| sex-linked genes | Genes located on a sex chromosome. |
| linked genes | Genes located on the same chromosome that tend to be inherited as a unit. |
| genetic recombination | The general term for the production of offspring with new combinations of traits inherited from two parents. |
| parental types | The phenotypes of the P generation in punnett square crosses. |
| recombinants | Offspring with new combinations. |
| genetic map | An ordered list of the genetic loci along a particular chromosome. |
| linkage map | A genetic map based of recombination frequencies. |
| map unit | Equal to a 1% recombination frequency. |
| cytological maps | Locate genes with respect to chromosomal features. |
| Duchenne muscular dystrophy | A sex-linked disorder that causes the progressive weakening of muscles and loss of coordination. |
| hemophilia | A sex-linked recessive trait defined by the absence of one or more of the proteins required for blood clotting. |
| Barr body | The inactive X in each cell of a female condenses into a compact object called a.. |
| nondisjunction | A mishap where chromosomes do not separate properly and one gamete receives two of the same type of chromosome while the other gamete receives none. |
| aneuploidy | When an aberrant gamete unites with a normal one during fertilization, producing an offspring with an abnormal chromosome number. |
| trisomic | When a cell has a triplicate of one chromosome (2n+1). |
| monosomic | When a cell is missing a chromosome (2n-1). |
| polyploidy | An alteration where an organism has more than two complete chromosome sets. |
| deletion | Occurs when a chromosomal fragment lacking a centromere is lost during cell division. |
| duplication | Occurs when an extra fragment is attached as a segment to a sister chromatid. |
| inversion | Occurs when a chromosomal fragment reattaches to the original chromosome, but in the reverse orientation. |
| translocation | Occurs when a fragment joins a nonhomologous chromosome. |
| Down syndrome | An aneuploid condition that is usually the result of an extra chromosome 21. |
| genomic imprinting | A process where a gene on one chromosome is silenced, while its allele on the homologous chromosome is left to be expressed. |
| fragile X syndrome | A disorder named after the appearance of the chromosome itself: the tip of it hangs on the the rest of the chromosome by a thin thread of DNA. This causes the most common form of mental retardation. |
