Transcript

TEXT ON SCREEN

Schematic representation of an E. coli bacterium. The region of the cytoplasm containing the single circular genomic DNA molecule is called the nucleoid. Between divisions, the bacterium grows by elongation from the middle of the cell, increasing cell mass. When the cell reaches a certain size, the circular DNA molecule is replicated (copied). The two DNA molecules each attach to a different part of the cell membrane, so that as the cell elongates, they segregate to opposite ends of the cell. The cell membrane constricts and new cell walls are formed at a point between the two DNA molecules. And the two identical cells finally separate.