The size and cell type of microbes Most of the bacteria,protozoa,and fungi are single-celled microorganisms,and even the multicelled microbes do not have a great range of cell types.Viruses are not even cells,just genetic material surrounded by a protein coat and incapable of independent existence. Most of the bacteria, protozoa, and fungi are single-celled microorganisms, and even the multicelled microbes do not have a great range of cell types. Viruses are not even cells, just genetic material surrounded by a protein coat and incapable of independent existence. The size and cell type of microbes