| Term | Definition |
|---|
| Nondisjunction | an error in meiosis or mitosis in which members of a pair of homologous choromosomes or a pair of sister chromatids fail to separate properly from each other |
| Aneuploidy | a chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number |
| Monosomic | referring to a cell that has only one copy of a particular chromosome instead of the normal two (example turner syndrome) |
| Trisomic | referring to a diploid cell that has three copies of a particular chromosome instead of the normal two [example down syndrome (trisomy 21)] |
| Polyploidy | a chromosomal alteration in which the organism possesses more than two complete chromosome sets, it is the result of an accident of cell division |
| Deletion | occurs when a chromosomal fragment is lost, the affected chromosome is then missing certain genes [example Cri-du-chat (missing part of chromosome 5)] |
| 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 |
| Inversion | an aberration in chromosome structure resulting from reattachement of a chromosomal fragment in a reverse orientation to the chromosome from which it originated |
| Translocation | an aberration in chromosome structure resulting from attachment of a chromosomal fragment to a nonhomologous chromosome |
| Reciprocal Translocation | (most common type) nonhomologous chromosomes exchange fragments |
| Nonreciprocal Translocation | a chromosome transfers a fragment without receiving a fragment in return |
| Down Syndrome | a human genetic disease caused by the presence of an extra chromosome 21 (trisomy 21), characterized by mental retardation and heart and respiratory defects |
| Karyotype | a display of the chromosome pairs of a cell arranged by size and shape (picture taken during metaphase) |
| Klinefelter Syndrome | an extra X chromosome in males (trisomy), patients characterized by subnormal intelligence, impotence, and some female characteristics |
| Turner Syndrome | an X chromosome is missing in females (monosomy), patients are sterile |
| Cri-du-chat | (cry of the cat) results from deletion of chromosome 5, patients are mentally retarded |
| Mutation | a change in the nucleotide sequence of an organism's DNA, ultimately creating genetic diversity, mutations also can occur in the DNA or RNA of a virus |
| Point Mutation | a change in a gene at a single nucleotide pair |
| Base-pair Substitution | a type of point mutation; the replacement of one nucleotide and its partner in the complementary DNA strand by another pair of nucleotides (can be either silent or missense) |
| Silent Mutation | because of the redundancy of the genetic code, the mutation has no effect on the encoded protein |
| Missense Mutation | a base-pair substitution that results in a codon that codes for a different amino acid |
| Nonsense Mutation | a mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein |
| Point Mutation: Insertion | a mutation involving the addition of one nucleotide pair to a gene |
| Point Mutation: Deletion | a mutational loss of one nucleotide pair from a gene |
| Frameshift Mutation | a mutation occurring when the number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper grouping of then subsequent nucleotides into codons (extensive missense) |
| Spontaneous Mutation | an incorrect base pair is added during replication and the error isnt corrected, the erroneous strand is then used as a template in the next round of mutation, about one nucleotide in every 10^10 is altered, and the change is passed on to the next generation of cells |
| Mutagen | a chemical or physical agent that interacts with DNA and causes a mutation |
| Carcinogen | known mutagen where the outcome is cancer |
Combine with other sets
Share on Facebook
Share on MySpace