Cell membrane lining the inner surface of the cell wall

The cell membrane lining the inner surface of the cell wall is made up of phospholipids (45%) and proteins (55%). Some E.coli cells have small thin filamentous extensions of the cell wall called the pili. While the cell wall serves to protect the organism from the external environment, it also allows small molecules and nutrients to selectively pass through. The cytoplasm of the cell is enclosed within the cell membrane. Within the cytoplasm lies a single molecule of double          stranded DNA in the form of an endless loop called circular DNA. The circular DNA molecule is tightly coiled to form the nuclear body (bacterial chromosome). In addition, most bacteria contain small circular fragments of DNA called the plasmids, which also carry genetic information independent of the bacterial chromosome.