PLPA 301 Study Guide - Midterm Guide: Thigmotropism, Chytridiomycetes, Hypha
20 Feb 2019
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*answers in red: give a definition of a fungus. Eukaryotic, heterotrophic, absorptive organisms that develop a rather diffuse, branched, tubular body and reproduce by means of spores . Hypha - basic unit; greek for web , a thread-like structure. Coenocytic hyphae - no cross wall; multinucleate hypha. Directional growth - fungi follow different types of directional growth - tropisms. Chemotropism - movement towards chemicals (nutrients), for example, in the rhizosphere (sugars etc. ) Autotropism - growth towards other members of the same species. Negative autotropism - growth away from members of the same species. The haploid, diploid or dikaryotic can be maintained by mitotic divisions. Sexual reproduction relies on meiosis: meiosis involves recombination between homologous chromosomes and is a key mechanism for increasing species diversity: ascospores (ascomycetes, oospores (oomycetes, zygospores (zygomycetes & chytridiomycetes, basidiospores (basidiomycetes) A sequence involving heterokaryon formation, diploid ization, and haploidization, often resulting in the formation of recombinant nuclei .
