a bacterium takes up a piece of DNA floating in its environment.
transduction
, viruses that infect bacteria move short pieces of chromosomal DNA from one bacterium to another "by accident."
enveloped viruses
viruses encased by a chunk of host cell membrane as they bud out of the cell, similar to exocytosis
conjugation
DNA is transferred from one bacterium to another. After the donor cell pulls itself close to the recipient using a structure called a pilus, DNA is transferred between cells. In most cases, this DNA is in the form of a plasmid.
transposable elements
chunks of DNA "jump" from one place to another within a genome, cutting and pasting themselves or inserting copies of themselves in new spots