Eukaryotes - Microbial Genetics

EUKARYOTES

Eukaryotic microorganisms (yeasts, moulds, algae and protozoa) possess a nucleus that normally contains one or more pairs of linear chromosomes, in which the ds DNA is complexed with protein. The cells may divide asexually and the nucleus undergoes mitosis—a sequence of events by which the nucleus and the chromosomes within it are replicated to give copies identical to the originals. Most eukaryotes also have the potential for sexual reproduction during which the nucleus undergoes meiosis, i.e. a more specialized form of nuclear and chromosome division creating new gene combinations, so the offspring differ from the parents. Despite this potential, there are some eukaryotic cells, particularly fungi, in which a sexual stage in the life cycle has never been observed. Many eukaryotic microorganisms possess plasmids, and some fungal plasmids are based on RNA instead of DNA.