Vocabulary
- Aneuploidy
- A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number.
- Barr Body
- A dense object lying along the inside of the nuclear envelope in female mammalian cells, representing an inactivated X chromosome.
- Chromosome Theory of Inheritance
- A basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.
- Crossing Over
- The reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis.
- Cytogenetic Map
- Chart of a chromosome that locates genes with respect to chromosomal features.
- Deletion
- (1) A deficiency in a chromosome resulting from the loss of a fragment through breakage. (2) A mutational loss of one or more nucleotide pairs from a gene.
- Down Syndrome
- A human genetic disease caused by presence of an extra chromosome 21; characterized by mental retardation and heart and respiratory defects.
- Duchenne Muscular Dystrophy
- A human genetic disease caused by a sex-linked recessive allele; characterized by progressive weakening and a loss of muscle tissue.
- Duplication
- An aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated.
- Genetic Map
- An ordered list of genetic loci (genes or other genetic markers) along a chromosome.
- Genetic Recombination
- General term for the production of offspring that combine traits of the two parents.
- Genomic Imprinting
- Phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent.
- Hemophilia
- A human genetic disease caused by a sex-linked recessive allele; characterized by excessive bleeding following injury.
- Inversion
- An aberration in chromosome structure resulting from reattachment in a reverse orientation of a chromosomal fragment to the chromosome from which the fragment originated.
- Linkage Map
- A genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes.
- Linked Genes
- Genes located close enough together on a chromosome to be usually inherited together.
- Map Unit
- A unit of measurement of the distance between genes. One map unit is equivalent to a 1% recombination frequency.
- Monosomic
- Referring to a cell that has only one copy of a particular chromosome, instead of the normal two.
- Nondisjunction
- An error in meiosis or mitosis, in which both members of a pair of homologous chromosomes or both sister chromatids fail to move apart properly.
- Parental Type
- An offspring with a phenotype that matches one of the parental phenotypes.
- Polyploidy
- A chromosomal alteration in which the organism possesses more than two complete chromosome sets.
- Recombinant
- An offspring whose phenotype differs from that of the parents; also called recombinant type.
- Sex-Linked Gene
- A gene located on a sex chromosome.
- Translocation
- (1) An aberration in chromosome structure resulting from attachment of a chromosomal fragment to a nonhomologous chromosome. (2) During protein synthesis, the third stage in the elongation cycle when the RNA carrying the growing polypeptide moves from the A site to the P site on the ribosome. (3) The transport of organic nutrients in the phloem of vascular plants.
- Trisomic
- Referring to a cell that has three copies of a particular chromosome, instead of the normal two.
- Wild Type
- An individual with the normal (most common) phenotype.
