Bacterial cells have no nucleus.
They are a lot smaller than plant or animal cells and have these features -
1) Chromosomal DNA (one long circular chromosome) controls the cell's activities and replication. It floats free in the cytoplasm (not in a nucleus).
2) Plasmids are small loops of extra DNA that aren't part of the chromosome. Plasmids contain genes for things like drug resistance, and can be passed between bacteria.
3) The flagellum (plural flagella) is a long, hair-like structure that rotates to make the bacterium move.