Structure of Fun-gi.

A fungus is comprised of a dense collection of hyphae in the stalk and head with an absorption network of hyphae called mycelium in the substrate.  Hyphae are made of tiny hollow tubes of plasma membrane and chitin filled with cytoplasm.  Parasitic hyphae invade host tissue by penetrating the membrane/cellwall with the tips of their hyphae; these types of hyphae are called haustoria.  In most fungi, the hyphae are subdivided by walls called septa (sing. septum).  These septa partition the hyphae and separate cellular regions; however, septa have large pores in them through which ribosomes, mitochondia, and even nuclei can pass freely.  Aseptate fungi have no septa with no barrier whatsoever divided "cells."  Thus aseptates are also known as coenocytes because repeated nuclear division occurred without cytoplasmic division.  The mycelium creates a large surface area for absorption - example:  10 cubic centimeters of soil may contain upwards of 1 kilometer of hyphae!  Out of that if the hyphae are 10 micrometers in diameter, the area in contact with the soil is 3.14 cubic meters!  The fungus' cell wall is composted of chitin making it strong and flexible. (Note:  chitin is a nitrogen-containing polysaccharide.)  

Next:  "Fungi Growth and Reproduction."