Chromosome
Package of DNA containing genetic material of an organism.
A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most important of these proteins are the histones. Chromosomes are visible under a light microscope only during the metaphase of cell division, where all chromosomes are aligned in the center of the cell in their condensed form. Chromosomal recombination during meiosis and subsequent sexual reproduction plays a crucial role in genetic diversity.
- field
- Genetics, Cell Biology
- known_for
- Packaging of DNA, vector of heredity, chromosome theory of inheritance
Lore & Background
The word chromosome comes from the Ancient Greek words χρῶμα (khrôma, 'colour') and σῶμα (sôma, 'body'), describing the strong staining produced by particular dyes. The term was coined by the German anatomist Heinrich Wilhelm Waldeyer, referring to the term 'chromatin', which was introduced by Walther Flemming. Otto Bütschli was the first scientist to recognize the structures now known as chromosomes. In a series of experiments beginning in the mid-1880s, Theodor Boveri gave definitive contributions to elucidating that chromosomes are the vectors of heredity, with two notions that became known as 'chromosome continuity' and 'chromosome individuality'. Wilhelm Roux suggested that every chromosome carries a different genetic configuration, and Boveri was able to test and confirm this hypothesis. Aided by the rediscovery at the start of the 1900s of Gregor Mendel's earlier experimental work, Boveri identified the connection between the rules of inheritance and the behaviour of the chromosomes.
Reader's Guide
Chromosomes are fundamental to heredity and genetic diversity. The chromosome theory of inheritance, named the Boveri–Sutton chromosome theory, linked the behavior of chromosomes during meiosis to Mendel's laws of inheritance. This theory was hotly contested by some famous geneticists, including William Bateson, Wilhelm Johannsen, Richard Goldschmidt and T.H. Morgan, but absolute proof came from chromosome maps in Morgan's own laboratory. Chromosomal instability and translocation can lead to mitotic catastrophe, usually causing apoptosis, but occasionally hampered by cell mutations that result in the progression of cancer. The study of chromosomes remains central to understanding genetics, cell division, and disease.
Did You Know?
- The term 'chromosome' was coined by German anatomist Heinrich Wilhelm Waldeyer.
- Otto Bütschli was the first scientist to recognize the structures now known as chromosomes.
- Prokaryotes typically have a single circular chromosome, but some bacteria have more than one chromosome.
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