![pearson protein scaffold chromosome pearson protein scaffold chromosome](https://image.slidesharecdn.com/16themolecularbasisofinheritance-130311053514-phpapp02/95/16-the-molecular-basis-of-inheritance-59-638.jpg)
The molecular structure of DNA became a key question. In 1944 it was realized that genetic transformation in bacteria was due to DNA and not protein and that DNA was the molecule responsible for heredity in genes and chromosomes. These studies reaffirmed that chromosome structure and behavior in somatic and germ cell divisions were common to all plants and animals. Cyril Darlington pioneered plant cytogenetics in 1920–30 Correspondence: Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UKĪnd made important advances in our understanding of mechanisms of chiasma formation and the behavior of sex chromosomes in meiosis. Morgan, Sturtevant, Bridges and Muller constructed the first genetic linkage maps from recombination studies in crosses made in the fruit fly and from cytological preparations of its polytene salivary gland chromosomes. Proof of the chromosomal theory of inheritance was a decisive event in biology that turned cytologists into cytogeneticists. Stains used by pathologists to identify bacteria also served to identify chromosomes. The mechanisms of transmission of both discontinuous and continuous characteristics across the generations were unknown before Mendel’s laws were explained at the turn of the 20th Century by the behavior of chromosomes in germ cells. The stage was set for ideas about the transmutability of species, the heritability of physical traits and Darwin’s theory of the origin of species. Variations in morphology within species, and to a greater extent between species, led Linnaeus and other taxonomists to classify all organisms in terms of genealogies with species, families and orders depending on their similarities, starting with individuals capable of reproduction that defined a species. While comparative anatomists had known for centuries that all animals share physical features that suggest a common structure among creatures both living and revealed in fossils, the cytologists of the 19th century found that this concept extended to a cellular organisation present in all plants and animals. Introduction Our specialty was pioneered by scientists who developed the compound microscope to study the cellular organisation of the living world. The future of molecular cytogenetics is likely to depend on a better knowledge of chromosome structure and function. The review provides a brief account of the structure of somatic and meiotic chromosomes, stressing the high conservation of structure in plants and animals, with emphasis on aspects that require further research. Improvements in the resolution of chromosome analysis has followed closely the introduction of innovative technology. History and evolution of cytogenetics Malcolm A Ferguson-SmithĪbstract The events that have led to the development of cytogenetics as a specialty within the life sciences are described, with special attention to the early history of human cytogenetics.