6.5 Bacteria & Viruses

Similarities of bacteria and viruses

• Both have a genome composed of nucleic acid

• Both are considerably smaller than eukaryotic cells

• Pathogenic viruses and bacteria are both adapted to take advantage of the conditions found inside other organisms

Difference of bacteria and viruses

• Bacteria are much larger than viruses (viruses are 20-400 nm, bacteria are 0.5 to 5 um)

• Bacteria are cell based organisms while viruses are not (they are small organic particles)

• Many structures present in bacteria are not present in viruses: large circular DNA, plasmids, ribosomes, cytoplasm, cell membrane, cell wall, flagella, pili

• Viruses have structures not present in bacteria: protein coat, linear genome that can be RNA or DNA

• Bacteria divide by binary fission, whereas viruses replicate using the host cells structures.

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