BIOL 112 EXAM 3 REVIEW (AutoRecovered).docx - BIOL 112 EXAM...

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BIOL 112 EXAM 3 REVIEW CHAPTER 24 FUNGI Structure of Fungi Body (THALLUS) is multicellular mycelium (except yeasts are unicellular) o Consist of HYPHAE (vast network of thread-like things SEPTATE fungi have hyphae with cross walls NONSEPTATE fungi are multinucleated Hyphae grow from tip o Gives the mycelium a large surface area per unit volume o NOTE! Cell walls = Chitin (like insect exoskeleton) Excess food stored as glycogen as in animals The HAPLOID stage of the fungus is the mature stage Fungi consist of MYCELIA (networks of branched hyphae adapted for absorption) o A mycelium’s structure maximizes its surface-to-volume ratio Most fungi have hyphae divided into cells by SEPTA, with pores allowing cell-to-cell movement of organelles (septate hyphae have pores that allow cytoplasm and other materials to flow) COENOCYTIV FUNGI lack septa and have a continuous cytoplasmic mass with hundreds or thousands of nuclei Specialized Hyphae in Mycorrhizal Fungi Some unique fungi have specialized hyphae called HAUSTORIA that allow them to penetrate the tissues of their host Hyphae can be adapted for trapping and killing prey The plant’s cell membrane is NOT destroyed Characteristics of the Fungi Mostly multicellular eukaryotes that share a common mode of nutrition o Heterotrophic o Cells release digestive enzymes and then ABSORB resultant nutrient molecules o Most are saprobes/ saprophytic (an organism that attains nutrition from dead or decaying matter) some are parasitic o Several are in mutualistic (both parties benefit) relationships with plants or other organisms o Biggest organism on Earth is a fungus Evolution of Fungi
Plants, animals, and fungi trace ancestry to PROTISTS Molecular data tells that animals and fungi shared a common ancestor after plants evolved o Animals and fungi are more closely related to each other than either is to plants o Flagellated unicellular protist (most likely the common ancestor) Fungal anatomy can’t easily be fossilized NOTE- The fossil record is biased since the more numerous an organism is and the harder an organism’s external anatomy/morphology is, the greater the likelihood the organism will become fossilized The Origin of Fungi Fungi, animals, and their protistan relatives from the OPISTHOKONTS clade Fungi evolved from a flagellated ancestor- although most fungi do NOT have flagella Nucleariids- amoeba that feed on bacteria and algae NOTE- 3 lines (on a phylogeny) implies a paraphyletic group DNA evidence suggests that o Fungi are most closely related to unicellular Nucleariids o Animals are most closely related to unicellular choanoflagellates STUDY PG 5 OF ANCILLARY FROM LAST EXAM!!!

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