Birgid Schlindwein's
Hypermedia Glossary Of Genetic Terms
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Birgid Schlindwein'sHypermedia Glossary Of Genetic TermsSearch Results |
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| Inversion | The term introduccd by Sturtevant (1926) for the reversal of the linear sequence of the genes in a segment of a chromosome. In an inversion heterozygote one of the chromosomes contributed by one parent has an inverted segment while the homologous chromosome contributed by the other parent has the normal gene sequence. |
| Base sequence | The order of nucleotide bases in a DNA molecule. Length is usually defined as the number of base pairs. Cf. sequence, DNA sequence. |
| Gene | The term coined by Johannsen (1909) for the fundamental physical and functional unit of heredity. The word gene was derived from De Vries' term pangen, itself a derivative of the word pangenesis which Darwin (1868) had coined. A gene is an ordered sequence of nucleotides located in a particular position (locus) on a particular chromosome that encodes a specific functional product (the gene product, i.e. a protein or RNA molecule). It includes regions involved in regulation of expression and regions that code for a specific functional product. See gene expression, allele. |
| Chromosome | The term was proposed by Waldeyer (1888) for the individual threads within a cell nucleus (gk. chroma, colour; soma, body). The self-replicating genetic structures of cells containing the cellular DNA that bears in its nucleotide sequence the linear array of genes. In prokaryotes, chromosomal DNA is circular, and the entire genome is carried on one chromosome. Eukaryotic genomes consist of a number of chromosomes whose DNA is associated with different kinds of proteins. |
| Heterozygote | The term coined by Bateson and Saunders (1902) for a zygote, or a diploid individual derived from it, which carries both members (Gk. heteros, different) of a pair of alleles. This might occur as a result of fusion of dissimilar gametes, or from mutation. Cf. heterozygosity |
| Homologous chromosome | A pair of chromosomes containing the same linear gene sequences, each derived from one parent. Humans normally have 22 pairs of homologous chromosomes and 2 X chromosomes (female) or 1 X and 1 Y chromosome (male). Compare sex chromosomes. |