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Unformatted text preview: reminder • the extra credit assignment can be turned in any 2me during the semester but the last possible 2me we will accept it is 5PM the last day of class (Fri. May 7) • We would appreciate it if you could turn it in well before this 2me so that we are not swamped with papers at the end. today’s factoid • The importance of underground life to Earth's ecosystem is the theme of NSF funded research by Dr. Diana Wall at Colorado State University Nematode worm species were found to be very abundant (89 diﬀerent species in 90 cubic cen2meters of soil from a tropical forest on Cameroon) were the predominant animals found in most soil environments Soil and sediment are cri2cal for agriculture human health ﬁsheries and aquaculture erosion control waste and water processing Used both tradi2onal whole animal iden2ﬁca2on (microscopy) and DNA based iden2ﬁca2on of biodiversity Rapid changes in species composi2on are found in Alaska, probably due to climate change hUp://www.nsf.gov/discoveries/disc_summ.jsp? cntn_id=115253&govDel=USNSF_51; see "Underground Life" story posted in Biology in the News on Blackboard • • • • • • • • • • • From a diﬀerent study of fungi and nematodes: hUp://fungalgenomes.org/blog/2007/11/this‐fungus‐will‐trap‐you‐if‐ you‐are‐a‐nematode/ Bacterial vs. Eukarote ﬂagella • Bacterial ﬂagellum – Single “ﬁbril” composed of ﬂagellin (protein) – Hook and basal body drive mo2on hUp://en.wikipedia.org/wiki/Image:Flagellum_base_diagram.svg • Eukaryote ﬂagellum – Independently evolved – Enclosed by plasma membrane – 9 pairs of microtubules surround 2 microtubules in the center hUp://ﬁg.cox.miami.edu/Faculty/Dana/ﬂagellum.jpg a brief review • Diploid and haploid • Mitosis: diploid parental cell duplicates its DNA (chromosome(s)) and divides once to yield two iden2cal daughter cells – Haploid cells can also duplicate via mitosis • Meiosis: diploid parental cell duplicates its DNA (chromosome(s)) and then goes through two divisions to yield four non‐iden2cal haploid progeny cells (gametes) Eukaryote reproduc2ve diversity: conjuga(on • One group that does this: Paramecia Macronucleus ‐ used for running the cell Micronucleus ‐ used for meiosis, reproduc2on • One group that does this: land plants and many other mul2cellular photosynthe2c eukaryotes Mul2cellular eukaryote reproduc2ve diversity: alterna2on of genera2ons between haploid and diploids gametophyte sporophyte Eukaryote reproduc2ve diversity: alterna2on of genera2ons: isomorphic life cycle • One group that does this: many chlorophytes such as the sea leUuce Ulva lactuca Isogamy: male and female gametes are not diﬀerent (this is the case for U. lactuca but not all isomorphic species; some have Anisogamy) Eukaryote reproduc2ve diversity: alterna2on of genera2ons: haplon2c life cycle • One group that does this: many chlorophytes such as Ulothrix hUp://bo2t.botany.wisc.edu/images/130/ Chlorophyta/Ulothrix_130_.jpg Eukaryote reproduc2ve diversity: what are we? • Diplon2c life cycle hUp://en.wikipedia.org/wiki/Image:Game2c_meiosis.png Now let’s… • Examine what is known about the evolu2onary rela2onships of major eukaryote groups • Map two important characters onto this phylogeny – photosynthesis/endosymbiont events – mul2cellularity • Point out some important organisms Chromalveolates 3˚ 2˚ Cryptophyte clade (not shown) 2˚ Endosymbio(c events leading to chloroplasts (probably not all of them) Excavates 2˚ Rhizaria Unikonts Opisthokonts Amoebozoans Plantae 1˚ Endosymbio(c event leading to mitochondria Mul(cellularity Unikonts Chromalveolates Plantae Excavates Rhizaria Opisthokonts Amoebozoans two strange terms • unikonts – “one” + “pole” ﬂagellum – Consists of the opisthokonts plus the amoebazoans • opisthokonts (“behind”+”pole”[ﬂagellum]) – i.e. suggests that the ﬂagellum is used for propulsion Animals Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans Land plants Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans Fungi Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans Lae1porus Kelp Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans hUp://www.orgs‐evolu2on‐knowledge.net/Index/Tapestry/Kelp.jpg Amoeba Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans Chlorophytes Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans Ulothrix Paramecium Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans Diatoms Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans Abundant in the oceans, and fresh water Cell walls contain silicon, preserve well as fossils Foraminiferans Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans Calcium carbonate shells Abundant in oceans Cause of limestone deposits in Earth’s crust Dinoﬂagellates Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans Photosynthesizers, vital primary producers in the oceans Unicellular, with two ﬂagella, one in each groove Some are symbionts of corals Trypanosomes Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans Plasmodium, the malaria parasite Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans • Zygote (in mosquito) ‐ very brief diploid stage • Sporozootes ‐ haploid • Gametocytes (in human), get transferred to the mosquito and develop into gametes, undergo fusion to form the zygote Fungi Chromalveolates Plantae Excavates Rhizaria Unikonts Opisthokonts Amoebozoans Lae1porus Fungal mutualism: two major modes • Mutualism is a symbio2c rela2onship that beneﬁts both partners – (by itself, symbiosis means a close, long‐term associa2on) • Lichens – Fungal associa2on with a photosynthe2c microbial organism (a unicellular green alga or cyanobacterium) • Mycorrhizae (pl., sing.=mycorrhiza) – Associa2ons between fungi and plant roots Lichens can survive in many harsh environments • Fungal component ‐ most are from the ascomycete clade (a clade is a monophyle2c group) • Most grow very slowly Anatomy of a foliose lichen; soredia • Many species (>15,000) (sing. soredium) have both components and disperse via wind. – Poorly understood A crustose lichen A foliose lichen A frui2cose lichen Reproduc2on also occurs by fragmenta2on Micorrhizal fungal associa2ons with plants are ubiquitous • Fungi help plant roots absorb water and nutrients (minerals) • Fungus obtains organic compounds from the plant • Two types – Ectomycorrhizae – Arbuscular mycorrhizae • Fungi wraps aroundroot • Hyphae enter root cells (like haustoria of fungal parasites) – Greatly adds to surface area – Vital for most plants Endophy2c fungi (endophytes) • Live on plants above the ground • Provide many beneﬁts to plants (e.g. resistance compounds) but some are pathogens • Some live within the leaves and other 2ssues Taxomyces andreanae, an endophyte found in the bark of the Paciﬁc Yew tree, was the original source of the an2cancer drug, taxol. Many leaf‐cuUer ant species are fungi farmers • Ants feed chewed up leaf material to fungal mycelia in their nests • Usually the “farm” is a single fungal individual (clone) – Fends oﬀ other fungi with an2fungal compounds produced by the fungus • (see experiment on page 658 of textbook) hUp://myrmecos.ﬁles.wordpress.com/2008/03/fungus1.jpg Fungal life cycles • Great diversity • Some have alterna2ng genera2ons (as in previous lecture) • Some have a dikaryon stage as part of an alterna2ng genera2ons life cycle The dikaryo(c stage is unique to fungi (but not all fungi have this stage) Basidiomycete life cycle • Basidiomycetes are most of the mushrooms producing species that we see • Don’t worry about the other life cycles on pp. 660‐663 Mushroom = ‘Basidiocarp’ ...
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This note was uploaded on 02/18/2010 for the course BIO 201 taught by Professor True during the Spring '08 term at SUNY Stony Brook.
- Spring '08