| frameshift mutation | <molecular biology> A type of mutation that results from insertion or deletion of a single nucleotide into, or from, an open reading frame in the normal DNA sequence. Normally, the genetic code is read in the wrong frame, three nucleotides at a time, and the entire sequence downstream of the mutation, is translated into a polypeptide with a garbled amino acid sequence from the mutated codon onwards. These mutations may be induced by certain types of mutagens or may occur spontaneously and usually result in the generation, downstream, of nonsense, chain termination codons. Synonym: addition mutation, addition-deletion mutation, deletion mutation, reading-frameshift mutation. (21 Jun 2000) |
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| lethal mutation | <genetics, molecular biology> Mutation that eventually results in the death of an organism carrying the mutation. (18 Nov 1997) |
| genetic | <biology> Pertaining to reproduction or to birth or origin. (07 May 1998) |
| genetic amplification | A process for producing an increase in pertinent genetic material, particularly for increasing the proportion of plasmid DNA to that of bacterial DNA. Includes the production of extrachromosomal copies of the genes for RNA. (05 Mar 2000) |
| genetic assimilation | <genetics> A situation in which a characteristic that is normally expressed only in certain environmental situations becomes fixed in a population so that it no longer requires environmental factors to be expressed. (07 May 1998) |
| genetic association | The occurrence together in a population, more often than can be readily explained by chance, of two or more traits of which at least one is known to be genetic. (05 Mar 2000) |
| genetic block | <biochemistry, molecular biology> An obstruction in a biochemical pathway caused by a mutation that has crippled production of an enzyme critical to the pathway. (07 May 1998) |
| genetic burden | The genetic debt due to harmful mutation but as yet undischarged. (In a large population of fixed size every mutation with diminished genetic fitness will eventually become extinct and depending on the details of inheritance and phenotype must be paid for by a fixed number of genetic deaths per mutation, the genetic debt.) (05 Mar 2000) |
| genetic carrier | An unaffected heterozygote bearing a usually harmful recessive gene, a cancer that bears a dominant but latent age-dependent trait to have offspring with unbalanced karyotypes. (05 Mar 2000) |
| genetic code | <molecular biology> Relationship between the sequence of bases in nucleic acid and the order of amino acids in the polypeptide synthesised from it. A sequence of three nucleic acid bases (a triplet) acts as a codeword (codon) for one amino acid. (18 Nov 1997) |
| genetic colonisation | <molecular biology> The process of a parasite (such as a virus) inserting genes into a host's genome which cause the host cell to synthesise products that are only useful to the parasite. (07 May 1998) |
| genetic complement | <biology, genetics> The set of chromosomes contained within any one particular cell. (07 May 1998) |
| genetic complementation | <genetics> The reappearance of wild-type characteristics in a cell or organism that has had two distinct mutations on the same chromosome. Two normal versions of two different mutant genes on different chromosomes affecting the same phenotype which, when inherited together, results in the wild-type phenotype despite the presence of mutant copies of the genes. (09 Oct 1997) |
| genetic complementation test | A test used to determine whether or not complementation (compensation in the form of dominance) will occur in a cell with a given mutant phenotype when another mutant genome, encoding the same mutant phenotype, is introduced into that cell. (12 Dec 1998) |
| genetic compound | In medical genetics, the presence of two different mutant alleles at the same loci. Synonym: genetic compound. (05 Mar 2000) |