Bio 1442 week 1 notes for exam 3
Bio 1442 week 1 notes for exam 3 BIOL 1442
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This 5 page Class Notes was uploaded by Kristin O'Flaherty on Wednesday April 6, 2016. The Class Notes belongs to BIOL 1442 at University of Texas at Arlington taught by Dr. Roelke in Winter 2016. Since its upload, it has received 62 views. For similar materials see Evolution and Ecology in Biology at University of Texas at Arlington.
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Date Created: 04/06/16
Week 1 Bio Notes CH 31: FUNGI Fungi are diverse and widespread They are essential for the wellbeing of most terrestrial ecosystems because they break down organic material and recycle vital nutrients About 100,000 species of fungi have been described It is estimated there are actually 1.5 million species of fungi Fungi are heterotrophs that feed by absorption Fungi exhibit diverse lifestyles o Decomposers o Parasites o Mutualists Most common body structures are multicellular filaments and single cells (yeasts) Some species grow as either filaments or yeasts; others grow as both Morphology of multicellular fungi enhances their ability to absorb nutrients Fungi consist of mycelia, networks of branched hyphae adapted for absorption A mycelium’s structure maximizes its surfacetovolume ratio Fungal cell walls contain chitin Most fungi have hyphae divided into cells by septa Coenocytic fungi lack septa Some fungi have specialized hyphae called haustoria that allow them to penetrate the tissues of their host Mycorrhizae are mutually beneficial relationships between fungi and plant roots Ectomycorrhizal fungi for sheaths of hyphae over a root Arbuscular mycorrhizal fungi extend hyphae through the cell walls of root cells and into tubes formed by invagination of the root cell membrane Fungi can produce spores from different types of life cycles Fungi propagate themselves by producing vast numbers of spores, either sexually or asexually Fungi use sexual signaling molecules called pheromones to communicate their mating type Plasmogamy is the union of cytoplasm from two parent mycelia In most fungi, the haploid nuclei from each parent do not fuse right away; they coexist in the mycelium called a heterokaryon In some fungi, the haploid nuclei pair off two to a cell; such a mycelium is said to be dikaryotic Hours days or even centuries may pass before the occurrence of karyogamy, nuclear fusion Become diploid Produce haploid cells Produces genetic variation Molds produce haploid spores by mitosis and form visible mycelia Yeasts can reproduce asexually Yeasts reproduce asexually by simple cell division and the pinching of “bud cells” from a parent cell Some fungi can grow yeasts and as filamentous mycelia Deuteromycetes are fungi that don't have a sexual stage Fungi are most closely related to unicellular nucleariids Animals are most closely related to unicellular choanoflagellates This suggests that multicellularity arose separately in animals and fungi The oldest undisputed fossils of fungi are only about 460 million years old (animals are about 700 million years old) Chytrids are responsible for amphibian deaths worldwide Fungi were among the earliest colonizers of land Fossil evidence indicates fungi form mutualistic relationships with early land plants Genomic analysis indicates genes involved in mycorrhizal formation, sym genes, were likely present in the common ancestor to land plants 3/30 Annelids are coelomates with bodies composed of a series fused rings The phylum Annelida was traditionally divided into three clades o Polychaeta o Oligochaeta o Hirun Errantians o Mobile marine things o Paddlelike structures Sedentarians o Less mobile Earthworms Ecdysozoans Nematodes are the most abundant multicellular animal on Earth Some species of nematodes are parasites Arthropods o ⅔ of every species known are arthropods o Hox genes arthropods=swiss army knife o Chelicerates Water scorpions, horseshoe crabs, spiders, dust mites o Myriapods Millipedes and centipedes Centipedes are carnivores o Pancrustacea Crustaceans live in the water Isopods (roley poleys) Krill are not shrimp Barnacles Hexapods insects Incomplete metamorphosis Complete metamorphosis Separate males and females o Echinodermsstarfish Water vascular system Radial symmetry with multiples of 5 o Holothuroidea: sea cucumbers o Chordata