Imagine a whole house filled full of baby peas. If the house is your little toe, the peas are the cells. Bacteria are about the simplest cells that exist today. A bacteria is a single, self-contained, living cell. When you get an infection, the bacteria are swimming around your big cells like little rowboats next to a large ship.
Bacteria are a lot simpler than human cells.
A bacterium consists of a outer wrapper called the cell membrane , and inside the membrane is a watery fluid called the cytoplasm . A E. Coli bacterium has a distinctive, capsule shape. The outer portion of the cell is the cell membrane, shown here in orange. In E. Coli there are actually two closely-spaced membranes protecting the cell. Inside the membrane is the cytoplasm made up of millions of enzyme, sugar, ATP and other molecules floating freely in water.