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Lampbrush chromosome. Lampbrush chromosome are a special form of chromosome found in the growing oocytes (immature eggs) of most animals, except mammals. They were first described by Walther Flemming and Ruckert in 1882. [1] Lampbrush chromosomes of tailed and tailless amphibians, birds and insects are described best of all.
Humans have one pair fewer chromosomes than the great apes. Human chromosome 2 appears to have resulted from the fusion of two ancestral chromosomes, and many of the genes of those two original chromosomes have been translocated to other chromosomes. Differences in number and position of satellites.
A well known balanced lethal system is the one fixed in the genus Triturus (containing the crested and the marbled newts). [4] Each of the homologous chromosomes of pair 1 (1A and 1B) has a different recessive deleterious allele on a non-recombining section of the chromosome. [2]
A metaphase cell positive for the BCR/ABL rearrangement using FISH. Cytogenetics is essentially a branch of genetics, but is also a part of cell biology/cytology (a subdivision of human anatomy), that is concerned with how the chromosomes relate to cell behaviour, particularly to their behaviour during mitosis and meiosis. [1]
These chromosomes consist of more than 1000 copies of the same chromatid that are aligned and produce alternating dark and light bands when stained. The dark bands are the chromomere. It is unknown when chromomeres first appear on the chromosome. Chromomeres can be observed best when chromosomes are highly condensed. [2]
Endoreduplication is commonly observed in cells responsible for the nourishment and protection of oocytes and embryos. It has been suggested that increased gene copy number might allow for the mass production of proteins required to meet the metabolic demands of embryogenesis and early development. [ 1 ]
Population genetics is a subfield of genetics that deals with genetic differences within and among populations, and is a part of evolutionary biology.Studies in this branch of biology examine such phenomena as adaptation, speciation, and population structure.
The number of B-chromosomes copied between cells within individual members of a plant population fluctuates. [8] For example, the sister species Aegilops speltoides and Aegilops mutica possess copies of B-chromosomes within their aerial tissues, while their roots exhibit an absence of these supernumerary chromosomes.