Human Cells

Abstract

Unit 2 describes very small organisms, called microorganisms, such as bacteria and yeast. The basic unit of living material is a cell and many microorganisms have just one cell. A bacterial cell is not much more than cytoplasm, a long strand of DNA, a cell-surface membrane and an outer wall. A yeast cell is not much more than cytoplasm, a nucleus, a large vacuole, a cell-surface membrane and an outer wall.