Plasmid
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A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, dou
Electron micrograph of a DNA fiber bundle, presumably of a single bacterial chromosome loop
Electron micrograph of a bacterial DNA plasmid (chromosome fragment)
Insulin
Virus
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A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria a
Plasmid
…the submission. Plasmids are considered replicons, units of DNA capable of replicating autonomously within a suitable host. However, plasmids, like viruses, are not generally classified as life. Plasmids are transmitted from one bacterium to another (even of another species) mostly through conjugation…
Structure of icosahedral adenovirus; electron micrograph with an illustration to show shape
Structure of chickenpox virus. They have a lipid envelope.
Transmission electron microscope image of a recreated 1918 influenza virus
Two rotaviruses: the one on the right is coated with antibodies that prevent its attachment to cells and infecting them.