Biol 204L Lab 3: Multicellular Organisms PDF

Lab #3: Multicellular Organisms – Stramenopiles, Rhodophytes, and Fungi Biol 204L Stramenopiles - Mostly aquatic - Main synapomorphy: minute, tubular hairs typically occurring along flagellum - Typically have 2 heterokont flagella (1 smooth, 1 with hairs) - Major groups: - Oomycota...

Lab #3: Multicellular Organisms – Stramenopiles, Rhodophytes, and Fungi Biol 204L Stramenopiles - Mostly aquatic - Main synapomorphy: minute, tubular hairs typically occurring along flagellum - Typically have 2 heterokont flagella (1 smooth, 1 with hairs) - Major groups: - Oomycota - Chromobionta  Oomycetes (water molds) Saprobic or parasitic Some cause serious plant diseases like downy mildew and potato blight Reproductive Structures: Zoosporangia – produce zoospores asexually Oogonia – produce oospores sexually Saprolegnia  Chromobionta (brown “plants”) - Aquatic photoautotrophs - Range in size from microscopic unicellular plankton to 60-foot-long kelp - Planktonic forms contribute up to 50% of primary production in marine ecosystems - Contain chlorophyll c and laminarin/chrysolaminarin oil for energy storage - Most have brownish compound fucoxanthin 4 main lineages, including: Phaeophyta – Brown algae Bacillariophyta – Diatoms  Phaeophyta (brown algae) - Multicellular, marine; includes kelp - Apomorphy: algin - component of cell walls, used as Macrocystis thickening agent in food and cosmetics Anatomy of a brown alga (float=pneumatocyst) Fucus Silvetia  Bacillariophyta (diatoms) Ecologically very important as primary producers supporting trophic webs, and as contributors to silica cycle in oceans Flagella are reduced or absent Ornate cell walls composed of silica Diatomaceous earth – fossilized cell walls that have economic use as filters and abrasive agents Multiple shapes, including centric and pennate Rhodophyta Rhodophyta (red algae) Mostly multicellular, marine photoautotrophs Contain chlorophyll d and water-soluble photosynthetic pigments called phycobilins Absence of motile cells (no flagellated cells) Cell walls contain carrageenan and agar – ingredients in paint, cosmetics, and food products like ice cream (not always red in color) Fungi  Fungal Form and Function Multicellular (mostly) & chemoheterotrophic Mostly saprobic, some parasitic, some mutualistic Cell wall made largely of chitin Elongate, tubular cells linked together to form hyphae Hyphae when massed together form a structure called a mycelium Feed by secreting digestive enzymes and absorbing the digested food products Fungi Motile Fungi include Chytrids Non-motile Fungi (most fungi) include Zygomycetes Glomeromycetes Ascomycetes Basidiomycetes Non-motile Fungi Two major apomorphies: Non-motile spores (lack flagella or cilia) Haplontic – multicellular vegetative body composed of haploid cells  “Zygomycetes” Reproduce sexually by fertilization of nuclei from different mating strains, producing a diploid zygosporangium Asexual haploid spores in structures called sporangiophores may form hyphae of either mating strain include Rhizopus (common bread mold) not monophyletic? Glomeromycetes Nearly all members are arbuscular mycorrhizae, which form a mutualistic relationship with the roots of land plants Fungus obtains organic compounds from the host plant as a food source, and in return the fungus increases absorptive efficiency for mineral nutrients Most trees and shrubs depend on this symbiotic relationship for mineral absorption Ascomycetes and Basidiomycetes Sister taxa Include most familiar fungi Major synapomorphy: septate, dikaryotic hyphae Dikaryotic—nuclei don’t fuse during sexual reproduction, so each hyphal cell contains two nuclei, one of each mating strain Ascomycetes Saccharomyces Penicillium Ascomycetes produce a sac-like structure called an ascus, within which are produced the haploid sexual spores called ascospores Peziza - Some ascomycetes can also produce asexual a cup haploid spores called conidia from fungus specialized structures called conidiophores Many economically important members— Saccharomyces yeast, morels, truffles, Penicillium; also Candida, ringworm  Lichens Symbiosis between a fungus (usually ascomycete) and alga (usually green alga) Diverse and important components of many ecosystems worldwide Often sensitive to air pollution - can be environmental indicators Some can survive extreme environmental conditions (e.g., barren rock at high latitudes and altitudes) Can be some of the first organisms to colonize new volcanic islands, creating soil allowing plants to later take hold  Basidiomycetes Dikaryotic hyphae largely make up the reproductive body Coprinus Agaricus (basidiocarp) After fertilization, a specialized structure called the basidium is produced which extrudes the haploid spores externally on tiny peg-like structures Some of the most familiar fungi, including “typical” mushrooms Lab Activity! Complete lab exercises (drawings and answers to questions) in lab notebooks Draw what you see! And always record microscope magnification SKIP 3.1 - Oomycota sample in jar to look at but not make wet mounts from 3.5: on microscope in back left corner of room SKIP 3.7 ONLY cover slips (and broken glass) go in sharps containers - NOT demonstration slides or blank slides from wet mounts Return pre-prepared demo slides to where you got them For wet mounts: discard cover slip in sharps container, rinse slide in sink, put in slide rack (separated from other slides so they don’t stick together after drying) Before next Lab Finish Lab #3 Read Lab #4 Pre-lab #4 Quiz Dissecting and Compound Microscopes