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Glossary Term
The genetic material of the nucleus, consisting of deoxyribonucleoprotein, which occurs in two forms during the phase between mitotic divisions: 1) as heterochromatin, seen as condensed, readily stainable clumps; 2) as euchromatin, dispersed lightly staining or nonstaining material. During mitotic division the chromatin condenses into chromosomes.
Glossary Term
A specific sequence of three adjacent bases on a strand of DNA or RNA that provides genetic code information for a particular amino acid.
Glossary Term
Variation in the number of copies of a particular sequence within the genetic material of an individual. Large-scale copy number polymorphisms are common and widely distributed in the human genome.
Glossary Term
A long linear double-stranded polymer formed from nucleotides attached to a deoxyribose backbone and found in the nucleus of a cell; associated with the transmission of genetic information.
Glossary Term
Changes in the regulation of the expression of gene activity without alteration of genetic structure.
Glossary Term
Genetic Variation consists of deviation(s) in the nucleotide sequence of the genetic material of an individual from that typical of the group to which the individual belongs, or deviation(s) in the nucleotide sequence of the genetic material of offspring from that of its parents.
Glossary Term
The process of exchange of genetic material between autonomous replicons, which depends on regions of extensive sequence homology between the participating DNA strands. This process involves double-strand breakage of one participant, resection of the break, and strand invasion, followed by formation, displacement and resolution of the Holliday junction. This process is involved in repairing broken DNA and creating combinations of genes that may be unique from the parent duplexes. Disruptions in this process can result in inviability, premature aging and predisposition to cancers and degenerative diseases.
Glossary Term
A genetic variation where gain, loss, or exchange of DNA results in monoallelic loss of function mutations in a diploid cell. In the context of tumor suppressor genes, where a single copy is sufficient for functionality, loss of function for the second allele is associated with tumorigenesis.
Glossary Term
Genomic instability associated with the presence of hypermutability in specific genetic marker regions resulting from defective DNA mismatch repair.
Glossary Term
Any transmissible change in the genetic material of an organism, which can result from radiation, viral infection, transposition, treatment with mutagenic chemicals and errors during DNA replication or meiosis. The effects of mutation range from single base changes to loss or gain of complete chromosomes. As many of the simpler alterations to DNA may be repaired, such changes are only heritable once the change is fixed in the DNA by the process of replication. Mutations may be associated with genetic diversity or with pathologies including cancer.
Glossary Term
One of the three possible ways of reading a nucleotide sequence. As the genetic code is read in nonoverlapping triplets (codons) there are three possible ways of translating a sequence of nucleotides into a protein, each with a different starting point.
Glossary Term
A genetic process in which single-stranded RNA with base sequence complementary to a region of plus strand DNA is synthesized by DNA-dependent RNA polymerases. Following the binding of RNA polymerase on DNA promoter regions, the RNA product is synthesized in a 5' to 3' direction, elongating RNA along the DNA strand as the polymerase proceeds, accompanied by unwinding and rewinding of the DNA template.
