Lecture 8.docx

Lecture 8: Multicellular Organisms – The way of Fungi Closest related relative other than animals is Fungi Fungi perform external digestion – secrete digestive enzyme & absorb small molecules From single cell to cell aggregates Looking back at the amoeba The amazing slime moulds Myxogastria (gla...

Lecture 8: Multicellular Organisms – The way of Fungi Closest related relative other than animals is Fungi Fungi perform external digestion – secrete digestive enzyme & absorb small molecules From single cell to cell aggregates Looking back at the amoeba The amazing slime moulds Myxogastria (glasmodial or acellular slime moulds) Individual amoeba move independently and grow through phagocytosis As conditions changes, single amoeba may aggregate into multicellular organisms Characterized by its remarkable ability to transition between different stages and adapt to diverse environmental conditions. And all without a brain (or a nervous system). How? Use of cellular cytoskeleton for information transfer from one part of the cell to another and for some cells provides a means of movement (as in amoeba) By fusing cells (forming syncitia), in essence one very large cell is formed with many nuclei and a more complex cytoskeleton, allowing for more complex movement and exploration of space. Basic rules still apply – find suitable environmental cues and use a pattern of stereotyped movements Metazoa Zoa = tissue Meta = after Protozoans Proto = before Zoans = tissues Fungi The main body of the fungus is the mesh of hyphae Although most fungi are microscopic, or the size of the button mushrooms, some are the biggest organisms on the planet There must be a lot of coordination for growth and movement to maintain coherence in fungi, as suggested by the activity of slime moulds, but the behavior of fungi has been poorly studied. Still they, like plants, show that a lot of sophisticated behavior can be achieved without a brain.