Hypermedia Glossary Of Genetic Terms
|Metaphase||Strasburger (1884) originally introduced this term for the stage of nulear division after (Gk. meta) the chromosomes (ch) have divided into chromatids, but from about 1905, with the realization that the chromosomes are already double when nuclear division begins, he used the term in the now universally adopted sense of the stage in mitosis or meiosis I or II during which the chromosomes are aligned along the equatorial (metaphase) plate (ep) of the cell and kinetochores come into contact with the microtubuli of the spindle apparatus (s).
|Mitosis||The most frequent process of nuclear division (karyokinesis) in cells that produces daughter cells that are genetically identical to each other and to the parent cell. The mitosis is divided into four (or five) phases: prophase, prometaphase, metaphase, anaphase, telophase. Mitosis and interphase make the cell cylcle.|
|Meiosis||The term coined by Farmer and Moore (1905) for the process of two consecutive cell divisions in the diploid progenitors of sex cells. Meiosis results in four rather than two daughter cells (gametes), each with a haploid set of each chromosome pair. In meiosis I the prophase is more complex than that of mitosis. Five different stages can be differentiated: leptotene, zygotene, pachytene, diplotene and diakinesis. Prophase is followed by metaphase I, anaphase I, telophase I and interkinesis. Meiosis II could be described as a haploid mitosis resulting in four haploid gametes.
|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.|
|Kinetochore||Structure forming at centromere during mitosis for binding microtubules.|
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