Explain why the nucleus is described as the 'control centre' of a eukaryotic cell, and explain how the genetic material in a bacterial cell differs from the genetic material found in the nucleus of a eukaryotic cell.

The nucleus is the control centre because it contains the cell’s DNA, which stores the instructions for making proteins. These proteins carry out and regulate all chemical reactions and processes in the cell, so the nucleus directs cell function.

In a bacterial cell the genetic material is not enclosed in a nucleus; the DNA lies freely in the cytoplasm. Bacteria also possess plasmids – small, circular DNA molecules separate from the chromosomal DNA – which can carry additional genes.