Around the nucleic acid core lies a protein coat , made up of units called capsomeres . Some viruses also have an envelope derived from the host cell membranes. The envelope may be either baggy or tight, depending upon the nature of the virus. Return to top of the page Microfungi All fungi are eukaryotic . It is also a major component of the exoskeleton of arthropods such as insects.
Fungi are heterotrophic .
Saprophytic fungi grow on dead organic matter. Parasitic fungi grow on living tissues. Yeasts are unicellular organisms that multiply by a process of budding A small swelling develops on the mother cell, and this develops to full size. The mother and daughter cell then split to form two independent cells. Moulds produce a mat of thread-like structures known as hyphae or mycelia .