|
|
NUCLEOID
Description: Genome refers to the sum of genetic material in an organism. The bacterial genome is composed of DNA and represents the bacterium's nucleoid. Unlike the eukaryotic nucleus, the bacterial nucleoid has no nuclear membrane or nucleoli. The bacterial nucleoid does not divide by mitosis, but the cytoplasmic membrane plays a role in DNA separation during bacterial replication. Since bacteria are haploid there is also no meiosis in bacteria. The nucleoid is the genetic material of the bacterium. Genes located along the DNA are transcribed into RNA that, in the case of mRNA, is then translated into protein at the ribosomes. DNA determines what proteins and enzymes an organism can synthesize and, what chemical reactions it is able to carry out. Appearance and Size: The nucleoid is one long, single molecule of double stranded, helical, supercoiled DNA. The two ends of the double-stranded DNA covalently bond together to form both a physical and genetic circle. The chromosome is generally around 1000 µm long and frequently contains as many as 3500 genes. E. coli , that is 2-3 µm in length has a chromosome approximately 1400 µm long.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
