In eukaryotic organisms — plants, animals and fungi — the major portion of DNA is present in the chromosomes which are well-organised structures and quite different from the prokaryotic counterparts. Besides the chromosomes, mitochondria of both plants and animals and the chloroplasts of green plants also contain DNA. Interesting is the fact that the organization and the nature of the [...]
A virus is a pathogenic agent, a infections particle, consisting of a core of nucleic acid (DNA or RNA) enclosed in a protein shell. Viruses are, in general, much smaller than bacteria and have a much smaller genome. But their genetic material is of many varieties, unknown in cellular organisms. Some of these are discussed here. Bacteriophage φX174 which attacks [...]
In this article we will discuss about the organisation of DNA in bacteria. The DNA of bacteria, e.g. E. coli, is a covalently closed circular molecule. It forms the bacterial chromosome, though this chromosome is much simpler in structure and in level of organization than the eukaryotic chromosomes of plants and animals. Also, each bacterial cell normally has a single [...]