A chromosome is an 'X' shaped gene which contains DNA, found inside living cells. Chromosomes are easily seen using a microscope and are normally invisible most of the time (tâ¦his period of time called 'interphase') but become visible when the cell starts to multiply.
Bacterial DNA â a circular chromosome plus plasmids. The DNA of most bacteria is contained in a single circular molecule, called the bacterial chromosome. The chromosome, along with several proteins and RNA molecules, forms an irregularly shaped structure called the nucleoid.This sits in the cytoplasm of the bacterial cell.In addition to the chromosome, bacteria often contain plasmids â small circular DNA molecules. Bacteria can pick up new plasmids from other bacterial cells (during conjugation) or from the environment.his sits in the cytoplasm of the bacterial cell. In addition to the chromosome, bacteria often contain plasmids â small circular DNA molecules. Bacteria can pick up new plasmids from other bacterial cells (during conjugation) or from the environment.
Furthermore, some bacteria have linear chromosomes. Borrelia 3 have linear chromosomes and most strains contain both linear and circular plasmids; most of the bacteria in the genus Streptomyces 4 have linear chromosomes and plasmids and some have circular plasmids as well. For example, linear DNA was precipitated in the most commonly used procedures for purifying bacterial plasmids, and the procedures for purifying chromosomal DNA relied upon the differential binding of ethidium bromide to sheared DNA fragments compared to circular DNA.