Bacterial cells can contain thousands of ribosomes , the sites of protein synthesis. The structural similarity of bacterial ribosomes to that of those found in eukaryotic mitochondria and chloroplasts has been interpreted as evidence of endosymbiotic theory . Plasmids are small, extrachromosomal DNA circles. Plasmids replicate independently of the chromosome carry genes that are not essential for cell survival but may give some advantage to an organism. For example, they can carry genes for antibiotic resistance and toxin production.
Plasmids are also very useful vehicles for genetic engineering.
The ability to produce spores is a type of cell differentiation involving precise genetic regulation of proteins. This process has now become a model system for studying how cells of higher organisms divide and differentiate. UV radiation chemical disinfectants the resistance of these spores has serious consequences and some very pathogenic bacteria have the ability to produce such spores. The spore contains DNA, a small amount of RNA and little free water. Classically, bacteria have been studied and considered as unicellular organisms, with few social and communication skills.