Bacteria

Virus

Larger than viruses

Much smaller than a bacteria

Reproduce by splitting in two

Do not reproduce like higher organisms - is constructed from a length of genetic material (DNA or RNA) wrapped in a coat of protein

Single cells

Not cells but a collection of proteins

Can be one of four shapes: round, rod, spiral or comma

A collection of chemicals

Live freely in water or soil

Inactive and harmless when outside the body

Live parasitically in the bodies of other organisms

Invade a host organism, get into it’s cells and take them over by copying itself and then multiplying

Feed, grow and respire

A collection of chemicals

Can be treated with antibiotics

Cannot be treated with antibiotics