LECTURE 3: DIVERSITY OF LIFE AND PROKARYOTES

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1 05/10/10 2:23 AM LECTURE 3: DIVERSITY OF LIFE AND PROKARYOTES Pre-Lecture Vocabulary Cell wall A relatively rigid structure that encloses cells of plants, fungi, many protists, and most prokaryotes. Gives these cells their shape and limits their expansion in hypotonic media Membrane-enclosed organelle Organized structures found in or on eukaryotic cells. Examples include ribosomes, nuclei, mitochondria, Golgi apparatus Nucleus The centrally located compartment of eukaryotic cells that is bounded by a double membrane and contains the chromosomes Cytoskeleton the network of microtubules and microfilaments that gives a eukaryotic cell its shape and its capacity to arrange its organelles and to move Photosynthesis ATP (adenosine triphosphate) an energy storage compound containing adenine, ribose and three phosphate groups. When it is formed from ADP, useful energy is stored; when it is broken down (to ADP or AMP), energy is released to drive endergonic reactions. Cellular respiration the catabolic pathways by which electrons are removed from various molecules and passed through intermediate electron carriers to O 2, generating H 2 O and releasing energy Taxon a biological group (specifically a species or a clade) that is given a name Glycolysis The enzymatic breakdown of glucose to pyruvic acid. One of the evolutionary oldest of the cellular energy-yielding mechanisms. Lecture Notes Lecture Outline Diversity of life o What is diversity o How is diversity measured o Which groups show the greatest diversity Prokaryotes o Prokaryotes vs eukaryotes o Cell structure and morphology o 3 challenges of life What is diversity? Diversity in life (degree of difference in: ) o Genetic variation (within a species?) o Species composition (within a community) o Interactions within and between ecosystems Biodiversity (more diverse = healthier) Species diversity o This is commonly reserved for indices that measure both the number of species in a habitat as well as their relative abundance We have no idea how many species of life exist today can t estimate the diversity of prokaryotes Prokaryotes first appeared in the Precambrian era million extant eukaryotic species Bacteria and Archaea s numbers are completely unknown ~99% of all species are extinct Most species live in the tropics (Neotropics brazil, etc)

2 Arthropods most diversity > plants > Molluscs > fungi > vertebrates(fish > reptiles & amphibians > birds > mammals) o Most taxonomists are vertebrate, invertebrate or fossil Man factors that control diversity o Area (In general doubling the area increases number of species by 10-25%) o Climate (Warm, wet areas have more species, not sure why) Other measures of diversity o So far we have focused on numeric diversity ie number of species o Genetic diversity = measure of genetic distance (=evolutionary separation) Prokaryotes show greatest o Functional diversity = differences in shape, size, and generally ways of making a living (types of food, places lived, etc) Prokaryotes show greatest Summary on diversity of life There are likely ~ 7-10 million extant species ~99% of Earth s species are extinct Diversity is greatest near equator on large landmasses with good(warm wet) climates Taxonomists have quantified animals/insects/beetles as most diverse Prokaryotes Are the earth s oldest organisms Two major groups o Bacteria o Archaea (which are closer to eukaryotes) Prokaryotes vs Eukaryotes Nucleus - Eukaryotes have, prokaryotes do not DNA - Prokaryotes have 1 chromosome (circular) and plasmids eukaryotes have linear chromosomes Membrane bound organelles - Prokaryotes do not have, eukaryotes hace Ribosomes - Prokaryotes have smaller (70s) (photosynthesis?), eukaryotes have larger (80s) Cytoskeleton - Prokaryotes no, eukaryotes have o Prokaryotic cells lack a cytoskeleton, and in the absence of organized cytoskeletal proteins, the lack mitosis. Prokaryotes divide by their own method, binary fission, after replicating their DNA Cell wall - prokaryotes yes (peptidoglycan in bacteria only), eukaryotes yes in some Photosynthesis prokaryotes yes (in some), eukaryotes yes (in some) Archaea Defining characteristics Know very little Absence of peptidoglycan in cell wall Distinctive lipids present in their cell membranes (not found in eukaryotes or bacteria) Many archaea also have lipid monolayer (cell membrane may be made of long chain hydrocarbons that span the membrane) Many archaea and bacteria have a single chromosome & plasmids o Chromosome not highly coiled o In nucleoid region o Plasmid extra-chromosonal DNA; small rings; easily exchanged during sex

3 Bacteria Bacteria do not have membrane-bound organelles Cell membrane is highly folded o This is where they perform cellular respiration (ATP synthesis) and photosynthesis Bacterial ribosomes are different than eukaryotes o Lack of nucleus, allows simultaneous transcription and translation = fast growth and reproduction Have variety of morphology o Unicellular, colonial o In spheres = cocci o Rods = bacilli o Helical = spirili Cell wall structure varies, which determines the results of Gram staining o Gram positive (purple) = thick cell wall with outer peptidoglycan layer o Gram negative (pink) = think cell wall between two membranes Typically antibiotics are ineffective against gram neg bacteria Bacteria and the three big challenges 1. Make nearly faithful copies of themselves (reproduce) Rapid, short generation times Asexual reproduction binary fission Sexual reproduction Genes on plasmids are easily transferred 3 main methods to obtain new genetic material a. conjugation bacteria form protein tube (sex pilus) and plasmids or even chromosomes are shared b. dead bacteria cells get absorbed c. viruses transfer genetic material 2. Respond to the outside environment by resisting internal changes in physical and chemical characteristics (maintain homeostasis) Respond to harsh environmental conditions Move towards or away from chemical signals = chemotaxis Use flagella (different from eukaryotes, rotates) a. Made from different protein b. Thinner and more numerous Also glide, roll, use gas floats inside cell Can from spore called endospore, which protect bacteria from adverse conditions (eg anthrax) Can form surface-coating communities called biofilms Form polysaccharide gell, trapping debris and other cells Can be hundreds of cells thick, and release signal molecules, attracting more Composed of single or many species Eg plaque, 3. Transform energy to synthesis new molecules (energy transformation) Despite their simplicity in cell structure, prokaryotes are extremely diverse in their metabolic abilities Variety due to diverse habitats and long evolutionary history

4 Prokaryotes can transform many different types of energy Light Organic and inorganic molecules o Autotrophs self feeding (use outside energy and inorganic material to make organic material) o Heterotrophs different feeding use organic molecules + outside energy to make new organic molecules Chemoheterotrophs consume organic molecules for carbon and E source (Make up most prokaryotes and other organisms) Are decomposers (make up most bacteria) " Decomposition is essential for nutrient recycling, eg salmon make symbiosis with eukaryotes " eg herbivores cannot digest cellulose and humans can t make vitamin K are pathogens " illness to host caused by bacterial toxins " exotoxins secreted proteins, very toxic (botulism- botox, tetanus) " endotoxins outer bacterial membrane, rarely fatal (Salmonella, E. coli) o Photoautotrophic transform light E into chemical E = photosynthesis Absorb light E with cholorophyll Use light E to convert CO 2 into glucose Produce O 2 as a waste product o Some bacteria are photoautotrophic but produce sulfur instead of oxygen (use hydrogen sulfide instead of water) Perform photosynthesis, but use other pigments to absorb different light wavelengths (400nm instead of 650nm) Produce S granules as waste product Purple sulfur bacteria are anaerobic Anaerobic vs aerobic metabolism Anaerobes do not require O 2 for metabolism Is the older metabolic pathway make ATP using fermentation, not cellular respiration obligate anaerobes O 2 is toxic facultative anaerobes use O 2 if available Autotolerant anaerobes can survive in O 2 environment, but do not use it Aerobes Must use O 2 for long term metabolism Nitrogen-fixing bacteria convert atmospheric N to NH 3 Plants are dependent on nitrogen-fixation Crop rotation often involves planting legumes Bacteria classification Traditionally based on shape and gram stain Now based more on DNA sequencing

5 LECTURE 4: PHYLOGENY, ORIGIN & DIVERSITY OF EUKARYOTES Pre-Lecture Vocabulary Taxonomy the branch of science concerned with classification of organisms Phylogeny the evolutionary history of a particular group of organisms or their genes Mitosis nuclear division in eukaryotes leading to the formation of two daughter nuclei, each with a chromosome complement identical to that of the original nucleus Meiosis Division of a diploid nucleus to produce for haploid daughter cells. The process consists of two successive nuclear divisions with only one cycle of chromosome replication. In meiosis I, homologous chromosomes separate but retain their chromatids. The second division meiosis II, is similar to mitosis, in which chromatids separate. Haploid having a single chromosome complement consisting of just one copy of each chromosome; designated 1n or n Diploid - Having a chromosome complement consisting of two copies (homologs) of each chromosome. Designated 2n Lecture notes Outline Taxonomy & phylogeny Origin of Eukaryotes Diversity of protists Taxonomy (the classification of life) How to organize? Binomial nomenclature o Genus species (Homo sapiens) o Hierarchy Kingdom, Phylum, Class, Order, Family, Genus, Species Kings play chess on finely grained sand Phylogenetic tree Root the common ancestor Node where genetic pathways branch, a common ancestor of those branches Clade a monophyletic group made of an ancestor and all of its descendants Sister group a pair of taxa (two phylogenic groups) that are each other s closest relatives Outgroup a closely related taxon but outside the group of interest

6 Monophyletic group an ancestor and all of its descendants Paraphyletic group a group that consists of an ancestor and some (but not all) of its descendants (eg Class Reptilia includes Lizards and crocodiles excludes birds) Polyphyletic group a group that consists of multiple distantly related organisms, and does not include the common ancestor of the group Analogy vs. Homology Homology similarity due to common ancestor Analogy similarity due to common environment o Convergent evolution Eg bat wing bone structure is homologous to human arm and bird bone structure Bat wing, insect wing and bird wing are analogous Shark and dolphin body form are analogous How to build a phylogeny Step 1 get a list of traits or characteristics for each taxon Step 2 (optional) identify order of progression of traits (jaw came after no jaw) and traits that show homology Step 3 let a computer find groupings (we try to find monophyletic groups Eukaryotes Eukaryotes Most life we see are eukaryotes Evolved 1-2 billion years ago after the formation of the O 2 atmosphere Differ from prokaryote ancestors o No cell wall or a non-peptidoglycan cell wall o Have membrane-enclosed organelles (eg nucleus, mitochondria, chloroplasts), larger ribosomes How to make a eukaryote from a prokaryote 1. Lose the cell wall 2. Infolding of the membrane # increased surface area 3. Form vacuoles by pinching membranes (ie lisosomes for digesting) 4. DNA & ribosomes are already attached to membrane; more infolding until they re surrounded # nucleus & endoplasmic reticulum (ER) 5. Build cytoskeleton 6. Extend cytoskeleton into flagellum & develop motion 7. Develop phagocytosis (engulfing cells or large particles) 8. Swallow a proteobacterium # mitochondria 9. Optional: swallow a cyanobacterium # chloroplast

7 Endosymbiosis One cell swallows a prokaryote but ends up living together instead of being digested Over a long time living together genome of the endosymbiont becomes very reduced, may move to the nuclear genome Evidence o Double cell membrane around mitochondria o Genes in mitochondria that match bacterial genes o Mitchondria & chloroplasts reproduce by binary fission independent of cell Inherit 100% of mitochondria (& chloroplasts) from mother s egg Suggested by Lynn Margulis in 60s and 70s Protists Eukaryotes are a monophyletic group Protists A term used out of convenience, not a taxonomic group Eukaryotes that are not plants, fungi or animal Size: microscopic Photoautotrophs, (chemo)heterotrophs Niches: free living endosymbionts, parasites Diverse method of locomotion ce, Mitochondria Chloroplasts Bacteria Archaea Plants Protist Protist Protist Protist Protist es Eukarya Animals Fungi DIVERSITY IN PROTISTS UNIKONTS single cone referring to single flagella (if present) may be close to the root of the eukaryotic tree examples: amoebas, slime molds and choanoflagellates Ameobas (loboseans) o Unicellular o Move via pseudopods (a temporary soft extension of the cell) & cytoplasmic streaming o May have test or hard shell o eat via phagocytosis o some are pathogenic ameobic dysentery 3 rd leading cause of death from parasites Slime molds o Most closely related to amoebas o Move by cytoplasmic streaming o Eat via phagocytosis o Form large aggregates o Reproduce via fruiting bodies and spores o Plasmodial slime mold - multinucleated, cells never divide o Cellular slime mold - come together as a large colony o Acellular - moves by pulsating.. gross Choanoflagellates o Choano=collar o Sister group to animals 28

8 o o Can be colonial Use flagella to capture prey RHIZARIA typically have long thin pseudopod, compared to amoebas Foraminiferans o Primarily marine o Secrete CaCO 2 test Formed major limestone deposits in ocean Used to date rocks, climate, identify oil rocks o Pseudopods stick out of test Capture prey Locomotion in some Radiolarians o Among the largest unicellular eukaryotic organisms o This, stiff pseuodopods stick out of test Assist in floating Increases surface area o SiO 2 tests Very ornate, unique Used as fossil markers o Marine zooplankton o Heterotrophs but often live symbiotically with phototrophic microbial eukaryotes (algae) EXCAVATES Once grouped together because some lacked mitochondria Metamonads (Parabasalids) o No mitochondria, anaerobic Originally thought to be primitive now know to have been lost (evolutionary reversal) as mitchondria DNA in nucleus o flagellated o symbionts (mutualistic & parasitic) o examples Giardia causes bever fever, Trichomonas cases STDs in humans Symbiont digesting wood in gut of termites Euglenids o Flagellated with flexible protein strips under membrane (pellicle) o Most are freshwater (with contractile vacuole to expel excess water in hypotonic environments) o Mode of nutrition Heterotrophic (phagocytosis) Photoautotrophic Some switch depending on environment PLANTAE Common ancestor was organism who underwent endosymbiosis engulfed a cyanobacteria Glaucophytes contain a small amount of peptidoglycan on inside and outside of choroplast membrane, same as cyanobacteria

9 Green algae (Chlorophytes) o Photoautotrophs o Diverse morphology Unicellular Colonial Multicellular filaments Multicellular sheets o Freshwater, marine, terrestrial o Can make daughter colonies and then mother cell will lyse o Share ancestor with land plant Cellulose in cell wall Store glucose as starch Have chlorophyll a and b Alternation of generations Red Algae o Multicellular, marine (most tropical) o Photoautotrophs o Accessory pigments Colour Ability to use different light wavelengths o Source of agar o Some secrete CaCO 3 coralline algae CHROMALCEOLATES Usually have cellulose in their cell walls Alveolates have sacs (aceoli) just below their plasma membrane (featured: ciliates, dinoflagellates and apocomplexans) Stramenophiles, most have flagella, one with hairs (featured: diatoms, brown algae and oomycetes) e two unequal 2 Ciliates o Possess cilia for locomotion and feeding o Unicellular, aquatic o photoautotrophs Heterotrophs, some have symbiosis with photoautotrophs micro & macronuclei more complex structure protection: protein pellicle control: 2 nuclei types feeding: oral groove, gullet defense: trichocysts H 2 O balance: contractile vacuole 43 o o o gullet Paramecium 44 trichocyts are tiny spears has complex feeding and excretions structures note contractile vacuole, necessary as ciliate is hypertonic in hypotonic environment

10 Acomplexians (obligate animal parasites) o Unicellular o Complex life cycles involving multiple hosts o Non-functional chloroplast o Coase of toxoplasmosis (contracted in cat feces) o Cause of malaria #1 infectious disease, affects red blood cells, transmitted by mosquitoes Dinoflagellates o Biflagellated marine phytoplankton o Major component of marine primary production (important base of food chain) Accessory pigments = gold-brown color o Unicellular Cellulose plates under membrane 2 flagella in perpendicular grooves o Adaptations Endosymbionic relationship with marine invertebrates called zooxanthallae coral bleaching spines reduce predation by zooplankton exhibit bioluminescence o some are non-photosynthetic & parasitic o some cause red tide release neurotoxins paralytic shellfish poisoning vertebrates most affected due to bioaccumulation Brown algae o Photoautotrophs o Multicellular, large o Marine, temperate, costal o Grow very quickly o Form kelp forests Extremely important habitat for many animals o Produce alginic acid (for anchorage to rock) o Gas bladders at base of blades provide buoyancy (can get sufficient light) Diatoms o Very important part of the phytoplankton o Unicellular o Photoautotroph o Cell walls of SiO 2 o Source of diatomaceous earth o Toothpaste, metal polishes, pool filters o Widely used in paleolimnology (study of lake sediments) different species are indicative of different environments Oomycetes o Water molds and downy mildews o Once classified as fungi (myco = fungus), but cell wall are cellulose o Unicellular but filamentous o Freshwater, some terrestrial o Absorptive heterotrops release enzymes to partially digest particles, then absorb into cell o some are decomposers ( saprobes, saprophytes) eat decaying organic matter o some are parasites (irish potato famine)

11 LECTURE 5: FUNGI Pre-Lecture Vocabulary Cytokinesis The division of the cytoplasm of a dividing cell Spore - Any asexual reproductive cell capable of developing into an adult organism with gametic fusion. In plants, haploid spores develop into gametophytes, diploid spore into sporophytes. Gamete the mature sexual reproductive cell: the egg or sperm union of gametes. Also known as syngamy Zygote The cell created by the union of two gametes, in which the gamete nuclei are also fused. The earliest stage of the diploid generation Outline 1. Fungi characteristics, symbioses, importance to ecosystem & phlogeny 2. General life cycles 3. Fungi diversity Fungi Absorptive heterotrophs Most are decomposers (saprobes) Cell wall of chitin Most are multicellular and terrestrial Produce spores (unicellular reproductive structures) Most of a fungus is underground o They would be susceptible to desiccation above ground Hyphae are filaments Fruiting bodies are formed for sexual reproduction o Produce spores by meiosis Spores can also be produced asexually o Commonly dispersed by wind and water Most fungi have a filamentous body plan o Long branged filaments = hyphae o Tangle mass of hyphae = mycelium o Provide large surface area - important for absorption 2 hyphal forms o septate have cross-walls (with pores to allow nutrient diffusion) o coenocytic no cell walls, multiple nuclei (these make up most fungi) have highly evolved hyphae o hyphae adapted for predation (eg hyphae rings that are adapted to trap and kill nematodes) o parasitism o mutualism with plants (can actually grow into place cells endo- type eg haustorium) Are extremely important to the growth and survival of plants o Mycorrhizae = mutualistic fungi that are associated with plant roots o Ecto-, endo- types o Fungus receives carbohydrates o Plant receives minerals, water (increases root s absorption) o The partnership of plants and mycorrhizae has a long history Scientists have found fossils of mychrrhizae that are older than vascular plants Fungi have mutualistic relationships with other organisms

12 o Lichens Fungus + cyanobacterium &/or unicellular green algae Are pioneer species in newly formed habitats Release acid and break down rock to form soil Food for tundra animals Diverse in morphology, color, species involved air pollution indicators sensitive to toxins in air as they are very absorptive o leaf cutter ants agricultural organisms feed fungi leaves, eat fungi some fungi are plant pathogens (corn smut, ergots on rye, maple leaves) and animal pathogens (ringworm, thrush, athlete s foot) Fungi phylogeny Flourished during Permian Closely related to animals o Was in domain of botanists for >100 years o ~ species known o phylogeny changing rapidly Fungi life cycles Many different ways of asexual reproduction o Production of haploid spores in sporangia o Production of haploid spores at tips of hyphae o Binary fission (yeast) o Breakage of mycelium o Haplontic life cycle - most of the life cycle is haploid, only the zygote is diploid General life cycle of plants alternates between haploid and diploid phases General life cycle of animals diplontic only gametes are haploid d. tween ses. General life cycle of fungi create mating types cannot mate with themselves, but no biological difference otherwise plasmogamy cytoplasm come together, but the nuclei do not fuse Dikaryotic phase is unique to fungi here the nuclei come together

13 General life cycle of fungi General life cycle of fungi mating type + mating type - General life cycle of fungi mating type + mating type - mating type + mating type - -gamy = union -gamy = union -gamy =syngamy union syngamy Basidiomycetes Basidiomycetes = club fungi = club fungi syngamy + Mating type + Mating type Plasmogamy Plasmogamy Mating Mycelial Mycelial hyphae Mating type Dikaryotic type Dikaryotic hyphae Basidiomycetes (club fungi) mycelium Basidiospores Mating structure (n +mycelium n) conidia Basidiospores terrestrial, aquatic Ascomycetes Germinating HAPLOID ascospores Gills fruiting bodies = basidocarps = sac fungi HAPLOID Gills Mating type a () DIKARYOTIC Basidium o mushrooms, puffballs, brackets + Mating type Ascomycetes Germinating Ascospores PlasmogamyBasidium DIKARYOTIC ascospores 30,000 species Gills lined Basidiocarp (n + n) = sac fungi withmating type A () or DIPLOID basidia Ascospores Mating Gills lined saprobes Mycelial Basidiocarp Basidioma type Ascospores Dikaryotic (2n) hyphae with (fruiting or DIPLOID o ectomycorrhizae mycelium structure) basidia Basidioma Basidiospores HAPLOID (2n) Meiosis (fruiting Ascospores Mitosis Ascus rusts & smuts structure) Plasmogamy Basidiomycetes = club fungi HAPLOID Basidium Meiosis Gills Nuclei nuclei DIKARYOTIC Developing Dikaryotic basidium ( n + n)mitosis M Ma HAPLOID (n Ascus mycelium Ascomycetes (sac fungi) Nuclei DIKARYOTICAscus DIPLOID Basidium Basidium Dikaryotic Developing (2n) asci (n + n) Meiosis Terrestrial, aquatic basidium ( n + n) Ascus Haploid Gills lined DIPLOID Basidiocarp Dik nuclei or hyphae (2n) with fruiting bodies contained in saces (asci) as Meiosis DIPLOID basidia Mating structure Basidioma nuclei conidia (2n) Ascomycetes (fruiting o morels, truffles Germinating Ascocarp or Ascoma ascospores structure) nuclei (fruiting structure) 64,000 species Meiosis = sac fungi Mating type a () o lichen (1/2 of species) Nuclei Basidium Ascospores Developing o brewer s & baker s yeast basidium ( n + n) Mating type A () Ascospores nuclei o mold & mildews penicillium HAPLOID aspergillus (soy, sake) Mitosis Ascus Plasmogamy naked spores (conidia) produced asexually in Glomeromycetes DIKARYOTIC Glomeromycetes Dikaryotic mycelium specialized hyphae (millions created) Ascus DIPLOID Dikaryotic (2n) Fewer than 200 sp. asci Fewer than 200Meiosis sp. terrestrial nuclei Glomeromycetes form endomycorrhizae with plants Aka Arbuscular mycorrhizae (small tree or shrub) shown to increase Fewer than 200 species plant s tolerance to stress and pathogens coenocytic Reproduce asexually, no known sexual stage Glomeromycetes terrestrial Haploid hyphae form endomycorrhizae with plants Ascocarp or Ascoma (fruiting structure) shown to increase plant s tolerance to stress and pathogens coenocytic Reproduce asexually, no known sexual stage

14 Rhizopus black bread mold Mitosis Ascus Plasmogamy DIKARYOTIC Ascus DIPLOID (2n) Dikaryotic Fungi phylogeny Zygomycetes asci Meiosis Zymycetes Chytrids Terrestrial Form endomycorrhizae with plants Sporangia Shown to increase plant s tolerance to stress (no fruiting bodies) Flourished during Permian (heat, drought, toxins) and pathogens Coenocytic (several nuclei) Spores asexually, Closely related animals Reproduce no known sexualto phase Hypha of mating type nuclei Spores Sporangium domain of botanists for >100Sporangiophore years HAPLOID >1000 species ~70,000 species known terrestrial parasitic, saprobic Meiosis form zygotes (2n) Rhizopus stolonifer spores contained in sporangia atop specialized hyphae Zygospore is highly resistant to harsh Multinucleate o no fruiting body zygospore within conditions. highly resistant to harsh conditions zygosporangium <1000 species paraphyletic group flagellated stages (only group) unicellular & multicellular stages mainly aquatic parasitic, saprobiv o largely responsible for amphibian decline no dikaryonic stage alteration of generations HA Mitosis Ascus DIPLOID (2n) Glomeromycetes Plasmogamy Zygosporangium Ascus Ascomycota Belong to several groups (zygo-, asco-, basidiomycetes) Basidiomycota Also have plasmids, useful in genetics Asexual reproduction by budding (only part of it splits off) or fission (parent cell divides roughly equally) Where did chitin evolve? Where did plasmogamy (fusion of plasma) prior to karygamy (fusion of nuclei) first appear DIP ( Meiosis Fewer than 200 sp. Haploid terrestrial Chytrids zoospores Sporangium Ascomycetes nuclei form endomycorrhizae = sac fungi Fertiliz Multicellular with plants haploid chytrid Karyo Meiosis shown to increase Female gametangium HAPLOID plant s tolerance to Female Male gametangiummitosis stress andmulticellular pathogens DIPLOID (2n) gamete diploid chytrid coenocytic (2n) Male gamete Meiosis Reproduce asexually, no known sexual stage No dikaryonic state Glomeromycota Ascospores Gametangia Germ asco Ascospores A Asc Ascus Phylogeny of the fungi Ascospores Ascocarp or Ascoma (fruiting structure) Germinating ascospores (n Haploid hyphae Hypha of + mating type Microsporidia Zygote Their relationship to other eukaryotes have (2n) puzzled taxonomists for decades th 8 ed Among the smallest eukaryotic organisms Lack mitochondria, but insteadchytridiomycota of mitosomes (derived from mitochondria but lack DNA) Common Unicellular ancestor Zygomycota Obligate intracellular parasites (have to live within another organism) Yeast Ascomycetes = sac fungi Dikaryotic mycelium Microsporidia nuclei 9th edition Glomeromycetes Glomeromycete Fewer than 200 sp. terrestrial form endomycorrhizae with plants shown to increase Reproduce asexually, known sexual stage plant s tolerance to stress and pathogens coenocytic Reproduce asexually, no known sexual stage Their relationship to other eukaryotes Fewer thanhave 200 sp. puzzled taxonomists for decades terrestrial Among smallest eukaryotic organisms form endomycorrhizae with plants Lack mitochondria, but instead have mitosomes shown todna) increase (derived from mitochondria but lack plant s tolerance to Unicellular stress and pathogens coenocytic Obligate intracellular parasites