In this article we will discuss about the relationship between genetic and cytological crossing over. The exchange of homologous segments of chromatids between homologous chromosomes during meiosis was cytologically demonstrated by Stern in 1931 in D. melanogaster and by Creighton and McClintock in the same year in maize. Stern used stocks of D. melanogaster carrying chromosomal structural changes. These stocks [...]
In this article we will discuss about the cell division and cell cycle in prokaryotes. Bacterial cell division is also termed as fission. The bacterial chromosome is circular and attached to the plasma membrane at a specific point. Its replication starts from an initiation point. Both the copies of the chromosome are attached to the plasma membrane, close to each [...]
In this article we will discuss about the chromosome movement during cell division. The chromosome movement during cell division is chiefly due to the spindle apparatus. This apparatus contains three different types of microtubules: (a) Astral microtubules, radiating from centrioles (found in animal cells only); (b) Continuous or inter-polar microtubules, passing from one pole to the other, account for the [...]