BIO 201 (LECTURE) Organismic Biology - Algae, Eukaryote, Multicellular Revolution, Prokaryotes, Plant Life Cycles, and Theories of Evolution
BIO 201 (LECTURE) Organismic Biology - Algae, Eukaryote, Multicellular Revolution, Prokaryotes, Plant Life Cycles, and Theories of Evolution BIO201
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Reviews for BIO 201 (LECTURE) Organismic Biology - Algae, Eukaryote, Multicellular Revolution, Prokaryotes, Plant Life Cycles, and Theories of Evolution
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Intro to Archaeplastidia (Plantae) Plant Life Cycles Algae: Glaucophytes, Rhodophytes BidlackChapter 12 and 18 Objectives • Understand the life cycle of a plant – Compared to animals – Compared amongst plant species • Understand how Glaucophytesand Rhodophytesrelate to land plants – Which one looks like a basal plantae? – Why? • Understand why Rhodophytesare red and why Which of the following is unicellular green algae? A. Chlamydomonas B. Volvox C. Oedogonium D. Spirogyra E. Ulva Polycystinea Acantharea SAR Foraminifera Vampyrellids Rhizaria Plasmodiophora Haplosporidia Core Cercozoa* Diatoms* Brown algae* Chrysophytes* Stramenopila Oomycetes Labyrinthulids Traversing Plantae Blastocystis Dinoflagellates* Apicomplexa* Alveolata Ciliates Haptophytes* Modern Centroheliozoa Glaucophytes* Plantae representatives of Red algae* Green algae* Cryptomonads* the first plants Euglenozoa* Excavata Heterolobosea Jakobids Preaxostyla Fornicata • Glaucophytes Parabasalia Malawimonas Thecamoebae • Rhodophytes Amoebozoa Vannellids Centramoebida Myxogastrids Dictyostelids Pelobionts Mastigamoebida Tubulinea by Kansas State University on 08/25/12. For personal use only.onas Apusomonads Breviata + Subulatomonas Annu. Rev. Microbiol. 2012.66. Downloaded from www.annualreviews.org Animals Opisthokonta Choanoflagellates Ichthyosporea Fungi Chytrids A quick guide to plant taxonomy Draw your own tree with character evolution!!! Glaucophyta Rhodophyta Algae Chlorophyta Mostly Aquatic Coleochaete (but not all!) Chara Hornworts Liverworts Mosses “Land Plants” Mostly Terrestrial Ferns (but not all!) Gymnosperms Angiosperms Evolutionary relationships among a lgae Chlorophyll (what type of a feature?) • Chlorophyll aas the ancestral state • Cyanobacteria use Phycobillinsand All use Chlorophylla plus: Chlorophyll a • Cladogram where different photosynthetic pigments can be mapped • Note the mis-placement of Euglenoids (why is this?) • Chlorophyll corganisms are in the SAR group • Cryptomonads use Chlorophyll c, but it is unclear where it came from; this organism is difficult to place – SAR versus adjacent to Archaeplastidia The complex biochemistry of plastids is due to secondary and tertiary endosymbiosis From: http://www.nature.com/scitable/topicpage/the-origin-of-plastids-14125758 Viridiplantae, Glaucophyta-Rhodophyta, and share similar characteris Phylum GlaRhodophyta-Viridiplantae, respectively)22). content,butdiffermarkedlyinsize[Fig.3A, tables We sequenced the mitochondrial genome S3 and S4, and discussion in the supporting online representatives of the first plants from C. paradoxaand from the distantly related material (SOM)]. A concatenated multiprotein • Gchloroplast containing speci lanta nostochinearu andgen- (17,049 aligned amino acid positions) phylogeny • Mto have evolvedt representative of the first plants – But why not? • Very few known speAies (<20 known) st p • Cyanophoraparadoxa – Genome sequenced Feb 201f s – Motile bi-flaggelate Cell wall n – Chloroplast biology p cb • 2 Chloroplasts per cell • Called Cyanelles m • Cyanobacteria “chloroplasts” but biologically more similar to • Cyanelles have cell walls5 µmt are biochemically similar to cyanobacteria – Where the cell wall be (think endosymbiosis)? Cyanophora paradoxa genome and the CORRECTED 16 MARCH 2012; SEE LAST PAGE origin of plants REPORTS sharing their kinematic models and GPS data for comparisonc and seismic data. The codes are available aFigs. S1 and S2 with the dynamic models, L. Wen for help with using hisfile as part of the supporting online material. Table S1 code, and three anonymous reviewers for their comments References (29–37) that substantially improved the manuscript. We are Supporting Online Material Computer Codes to UNAVCO, Incorporated Research Institutions for Swww.sciencemag.org/cgi/content/full/335/6070/838/DC1 NSF-EarthScope, International GNSS Service, NASA, aMethods 20 September 2011; accepted 24 January 2012 countless researchers for facilitation and availabiSOM Text 10.1126/science.1214209 reinhardtii(20, 21). Phylogenomic analysis of Cyanophora paradoxa Genome the predictedC. paradoxaproteins showed 274 to be of cyanobacterial provenance2(2). This Elucidates Origin of Photosynthesis constitutes ~6% of proteins in the glaucophyte that have significant BLASTp hits (i.e., 274 out of 4628), as found in other algae2(0, 21). BLASTp in Algae and Plants analysis identified 2029 proteins that are puta- tively destined for the plastid, of which 293 con- Dana C. Price, Cheong Xin Chan, * Hwan Su Yoon, 2,3Eun Chan Yang, Huan Qiu, 2 tainthetransit sequence for plastidimport [identified 4 5 1 6 6 Andreas P. M. Weber, 7ainer Schwacke, Jefe8son Gross, Nicolas A. Blou8n, Chris Lane, 9 by the presence of phenylalanine (F) within the Adrián Reyes-Prieto, Dion G. Durnford, Jonathan A. D. Neilson, B. Franz Lang, first four amino acids: MF, MAF, MNAF, MSAF, Gertraud Burger, Jürgen M. Steiner, 10 Wolfgang Löffelhardt, 11 Jonathan E. Meuser, 12 13 14 14 15 and MAAF] (23, 24)g (fi.S4Btese293 Matthew C. Posewitz,15 Steven Ball, Ma16,17,18lia Arias, Bernard He16,17at, proteins, 80% are derived from Cyanobacteria. Pedro M. Coutinho, Stefan A. Rensing, Aikaterini Symeonidi, Another source of foreign genes in Plantae Harshavardhan Doddapaneni, 19 Beverley R. Green, 20 Veeran D. Rajah, 1 21,22 1 is horizontal gene transfer (HGT), which is not Jeffrey Boore, Debashish Bhattacharya † associated with endosymbiosis. Using 35,126 bacterial sequences as a query, we found 444 The primary endosymbiotic origin of the plastid inuekaryotes more than 1 billion years ago led to the noncyanobacterial gene families with a common evolution of algae and plants. We analyzed draft genome and transcriptome data from the basally origin shared amongst Bacteria andPlantae. Among on August 29, 2012 diverging algaCyanophora paradoxaand provide evidence for a single origin of the primary plastid in the them, 15 genes are present in all three Plantae eukaryote supergroup PlantaeC.. paradoxaretains ancestral features of starch biosynthesis, fermentation, phyla. An example of a gene derived from Bacte- and plastid protein translocation common to plants andlgae but lacks typical eukaryotic light-harvesting ria after an ancient HGT event that is shared by complex proteins. Traces of an ancient link to paritaess such as Chlamydiae were found in the genomes of C. paradoxaand other Plantae. Apparently,Chlamydia-like bacteria donated genes that allow export Department of Ecology, Evolution, and Natural Resources and of photosynthate from the plastid and its polymeriztion into storage polysaccharide in the cytosol. Institute of Marine and Coastal Sciences, Rutgers University, NewBrunswick,NJ08901,USA.BigelowLaboratoryforOcean 3 ukaryoteevolutionhaslargely beenshaped test Plantae monophyly, we have generated a draft Sciences, West Boothbay Harbor, ME 04575, USA.rt- by the process of primary endosymbiosis, assembly of the≈70 Mbp nuclear genome from the ment of Biolo4ical Sciences, Sungkyunkwan University, Suwww.sciencemag.org 440-746, Korea.nstitute for Plant Bioch5mistry, Heinrich- E whereby bacterial cells were taken up and glaucophyte Cyanophora paradoxaCCMP329 Heine-University, D-40225 Duesseldorf, Germany.al over time evolved into double membran– ebound (Pringsheim strain) (Fig. 1A). Institute, Biocenter Cologne, University of Cologne, Zülpicher organelles, the plastid and the mitochondrion Atotalof27,921 C. paradoxaproteins were Strasse 47b, 50674 Cologne, Germany.rtment of Bio- logicalSciences,UniversityofRhodeIsland,Kingston,RI02881, The Cyanophora genome roots the monophyly of the plant lineage Phylum Rhodophyta • The red algae – Colors mostly due to phycobilins. • Similar to those of cyanobacteria – Red algaecannot be fully resolved from Glaucophytes at the base of the Planta tree – Chlorophylls a, and sometimes d – Food reserve - Floridean starch – Number of species produce agar. Phylum Rhodophyta • The red algae – In warmer and deeper waters than brown algae – Most are filamentous with filaments so tightly packed they appear to have flattened blades or branched segments. Phylum Rhodophyta • The red algae Polysiphonia – Relatively complex life cycle involving three types of thallus structures – Nonmotile reproductive cells Chlorophyll acquisition, Glaucophyta Chlorophyll a, Phycobilins Rhodophyta Chlorophyta Chlorophyll a, Chlorophyll b Coleochaete Chara Hornworts Liverworts Mosses Ferns Gymnosperms Angiosperms Which of the following are most representative of the first Plantae (Archeaeplastidia)? A. Rhodophyta B. Glaucophyta C. Cyanobacteria D. Green algae What is the key difference between asexual reproduction (mitosis) and sexual reproduction (meiosis)? A. They are the same B. Crossing over C. Chromosome partitioning D. Cell division Introduction • Asexual reproduction - Production of cells identical in chromosomes with cells from which they arose • Sexual reproduction - In nearly all plants, some algae (cryptic) – Results in formation of seeds in flowering and cone- bearing plants – Gametes produced. • Egg and sperm unite to form zygote. Asexual and Sexual Reproduction Plantsdo BOTH to make offspring Comparing Mitosis/Meiosis On your own, review the stages in Bidlack Chapters 3 and 12 Mitosis Meiosis • Chromosomes replicate • Chromosomes cross-over and themselves undergo “reductive division” • Then undergo a duplication • One copy of each to • Four cells from two daughter cells successive divisions – Cells with half the – 1n -> 1n chromosome number of – 2n -> 2n parents – 3n -> 3n – Each cell rarely identical to original cell or each other. – 4n -> 4n • 1n -> 1n + 1n (extra mitosis) • 2n -> 1n + 1n • 3n -> 1n + 2n (usually) • 4n -> 2n + 2n Meiosis Review • Before meiosis, DNA molecules of each chromosome double. – Each chromosome has identical DNA molecules held together by a centromere. • Meiosis: – Division I (Meiosis I or Reduction Division) - Number of chromosomes reduced to half. – Division II (Meiosis II or Equational Division) - No further reduction in chromosome number. Alternation of Generations • Haploid (1n) - Cell with one set of chromosomes – Gametes • Diploid (2n) - Cell with two sets of chromosomes – Zygote • Polyploid - Cell with more than two sets of chromosomes – Triploid3n) - Three sets of chromosomes • Homologous chromosomes cannot pair properly, thus gametes typically inviable. • Navel oranges, seedlesswatermelons – Tetraploi(d4n) - Four sets of chromosomes • Potatoes,pasta wheat Alternation of Generations • Athat alternates between diploid sporophyte phase and haploidoduction gametophyte phase • BOTH the sporophyte and gametophyte can live independently • BOTH the sporophyte and gametophyte can be multicellular and look like a plant – Sporophytes developfromzygotesandproduce sporocytes. • Sporocyte undergoes meiosis - Produces 4 haploid spores Meiosis occurs Mitosis results in in specialized sporophyte growth cells to produce spores Mitosis results in Mitosis occurs in gametophyte specialized cells to produce growth Alternation of Generations – Gametophytes develop from spores. • Form cells or sexual structures in which gametes are formed by mitosis – Fertilization produces ygote. • Fertilization ( syngamy) = Fusion of gametes Alternation of Generations • First cell of gametophytegeneration is a spore, and last is a gamete. • Any gametophytecell is haploid. • First cell of sporophyte generationis a zygote, and last cell is a sporocyte. • Any sporocyte cell is diploid. Alternation of Generations • Change from sporophyteto gametophyte generation occurs as a result of meiosis. • Change from gametophyteto sporophyte occurs as a result of fertilization. For most of the plant section you MUST understand alternation of generations! Our discussions will revolve around the evolution of plant life cycles In alternation of generations… a) 2n gametophytes produce sporesby meiosis b) 2n gametophytes produce gametes by meiosis c) 1n gametophytes produce sporesby meiosis d) 1n gametophytes produce gametes by meiosis e) Gametophytes do not undergo meiosis The Theories of Evolution Underlie the T ree of Life Objectives • Understand how evolutionary theory was developed • Understand the primary theories of evolution • Understand the basic structure of the tree of life • Know and be able to describe the primary features of each kingdom of life Evolutionary Theory • An intellectual framework for understanding how life and biodiversity came to be • Utilizes the scientific method to test how evolution worked and is currentlyworking. • Utilizes a vast array of approaches and methods – “Modern synthesis” Jean Baptiste de Lamarck • Attempted to explain the relatedness or organisms recognizing • Attempted to determine a mechanism by which modern forms derived from ancient forms • Lamarckian hypotheses: – Inheritance of acquired characteristics – Multiple independent origins of species Why Darwin was different and revolutionary • Proposed a single common ancestor for ALL organisms • Natural selection • Implies descent with modification • Proposed a mechanism of evolution • Implies a heredity mechanism • Never actually answered what the “Origin of Species” is (ironically) Darwin’s Five Evolutionary Theories Evolution is ot a single theory. Modern evolutionary theory is a collection of many inter- related theories. Darwin’s five contributions 1. Perpetual change 2. Common descent 3. Multiplication of species 4. Natural selection 5. Gradualism Perpetual Change • Life is not constant over time – Extensive fossil record – Life forms over human history are constantly changing – Life forms over human life times are constantly changing • Life is not cycling between two, or several states • Life forms are constantlychanging in response to their environment • Thus, what is today will not necessarily be tomorrow Perpetual Change in Kansas Cretaceous: mosasaurs, toothedbirds Pleistocene: mammoths, giant ground sloths, sabre-toothedcats Common Descent • All organisms descended from a single common ancestor • Ubetween species assumed independent originsationships • Cbetween organismsdicts a tree like structural relationship • Korganisms back and infer their phylogenetic relationship through homology • Note: Darwin’s theories do not deal with the Origin of Life first cell evolved.ly deal with what happened after the Common Descent: Homology • At its essence homology means that like structuresin different organisms derived from their common ancestor • In the modern genetic era, we how have vast quantities of evidence demonstrating shared characters result from the genes of a common origin = homologous genes . Common Descent : Homology Character DNA Phylogeny Phylogeny Integrative Question to Ponder: Why the disagreement? Multiplication of Species • Variation between individuals in a populations leads to reproductive isolation • Reproductive isolation = eciation • Reproductive barriers form between individuals in a population – Requires a physical barrier t-breeding – Often occurs in geographically separate populations Eucidaris tribuloides Eucidaris thouarsii Rate of Evolution: Gradualism: Speciation occurs though the gradual accumulation of small, incremental changes. Punctuated Equilibrium : Rapid, episodic speciation Little change over time m Continual, T gradual change over Rapid change over time short time Gradualism Punctuated equilibrium Divergence Divergence Natural Selection: Process by which certain adaptations are favored over time, leading to evolutionary change. Five observations and three inferences of Darwin . 1) Organisms have great potential for reproduction (exponential growth) 2) Natural populations don ot grow unchecked (logistic growth ) 3) Natural resources are limited (K = carrying capacity) 4) All organisms show variation in characteristics 5) Variation is heritable and can be passed to offspring Three major inferences 1) Competition among individuals 2) Differential survival and reproduction = fitness 3) Natural selectionleads to new new adaptations and species (parallels toartificial selecti)n Rapid evolution in recent history Peppered Moth Biston betularia Changes in frequency of color morphs The Modern View of Evolutionary Theory: Neo -Darwinism Modern Synthesis Comprehensive tools = paleontology, biogeography, genomics, population genetics, embryology, behavior, and systematics Macroevolution= origin, radiation and extinction of species Microevolution= changes in gene frequencies among generations at short time scales Antibiotic-resistant bacteria VRE = Vancomycin -resistant nterococcus MRSA = Methicillin -resistant taphylococcus aureus 1. Genetic drift Bottlenecks among cheetahs in Africa 2. Nonrandom mating Inbreeding in prairie chickens Processes of Microevolution 3. Natural selection Stabilizing Disruptive Directional 4. Migration Genetic drift and selection promote divergence among populations. Migration promotes mixing. Three domain tree of life ( Wooseet al 1990) Genomics: Confirmation of the topology of the tree of life Ding G, Yu Z, Zhao J, Wang Z, et al. (2008) Tree of Life Based on GenoPLoS ONE 3(10): e3357. doi:10.1371/journal.pone.0003357 On your own: • Review the methods and evidence of evolution (Hickman pgs 13-6), you ARE responsible for this information Algae BidlackChapter 18 Exam I • Wednesday, 9/16, during class • Lectures 1-8 (including today) • Study guide posted today • About 50 questions • Multiple Choice • Using old exams to study is not a good idea • Exam I review – Monday, 9/14 – 7p in 114 Ackert (Lab Room) Hospitals are a major source of antibiotic resistant bacteria • http://goo.gl/eDUJEx • Integrate what you know about evolution while you read this! Objectives • Understand the life cycle of the prototypical algae –the Volvocales – Unicellular vs. Multicellular species – Life cycle • Vegetative • Isogamy vs. Anisogamy • Know the life cycles of representative species of – Chlorophyta • Chlorophyceae • Ulvophyceae • Trebouxiophyceae • Charophyceae – steps toward aterrestrial lifestyle! – Kleptocracy • Sea slugs • Secondary/Tertiary endosymbioticplastids – Stramenopila – Alveolata – Euglenophyta – Others ? Stramenopila Alveolata Chlorophyta Phylum Chlorophyta • Green algae – Prototypical algae – Morphology range: unicellular, filamentous, platelike colonies, netlike tubes, hollow spheres, lettuce-like leaves • Greatest variety in freshwater lakes, ponds, and streams – Some on tree bark, in animal fur, in snowbanks, in flatworms or sponges, on rocks, in lichen “partnerships.” • Have chlorophylls a and b • Store food as starch • Most have a single nucleus per cell. • Most reproduce both sexually and asexually. Phylum Chlorophyta – Class Chlorophyceae • Chlamydomonas – Common inhabitant transient puddles and in moist soil • Why not open ponds? – Unicellular – Pair of whip-like flagella on one end pull cell through water. • Two or more vacuoles at base of flagella – Regulate water content of cell and remove waste • Single, cup-shaped chloroplast with one or two pyrenoids inside – Pyrenoids – RuBisCo, Proteinaceous structures associated with synthesis of starch • Red eyespot near base of flagella – Allows alga to swim toward light Phylum Chlorophyta – Class Chlorophyceae • Volvox – Colonialgreen algae held togetherin a secretion of gelatinous material, resembling hollow ball • Reproduction asexual or sexual – colonies formed inside parent colony The Evolution of Sex in the Volvocales Isogamous = same sized gametes Anisogamou= unequal sized gametes True eggs and sperm Isogamous sexual vs. vegetative cycles in the Volvocales • Lack of nitrogen ( -N) induces gametogenesis • Matting occurs (which part of Alteration of Generations?) • Zygote is very resistant to harsh environments • e.g. winter, drought etc. • Zygotes also are “sticky” and readily adhere to the feet of Anisogamoussexual cycles vs. vegetative life cycles in the Volvocales Volvox gametogenesis is induced by a sex inducr ()ot Sex inducer is produced in response to high Volvox concentrations, stress etc. Phylum Chlorophyta - Chlorophyceae • Oedogonium – Epiphytic filamentous green alga with holdfast – Large netlike chloroplast with pyrenoids at intersections of net – What distinguishes Oedogonium from Anabaena? – Asexual reproduction: • By fragmentation or by zoospores • Zoospores produced filaments.cells at tips of – Have about 120 flagella that form fringe toward one end of zoospore Phylum Chlorophyta - Chlorophyceae • Oedogonium sexual reproduction: – Exhibits oogamy - One gamete is motile, while other is larger and stationary. • Antheridium- Boxlike cell that produces two motile sperm • Oogonium - Swollen cell containing single egg – Sperm enters oogonium through pore. – Zygote forms thick walls and may remain dormant. – Zygote produces 4 zoospores by meiosis that grow into new haploid filaments. Phylum Chlorophyta - Trebouxiophyceae • Other green algae – Chlorella - Widespread green alga composed of tiny spherical cells • Only reproduce asexually by forming either daughter cells through mitosis • Lots of vitamins, especially vit C • Chlorella lysates are used as nutritional supplements Phylum Chlorophyta - Ulvophyceae • Other green algae – Acetabularia (mermaid’s wineglass) - Consists of a single, huge cell shaped like a delicate mushroom • Used in classic experiments demonstrating influence of nucleus on form of cell • Isogamous Acetabularialife cycle Even though it is unicellular is has complex tissues as if it were multicellular! Where is the line between unicellular and multicellular? What advantages would being a giant cell impart? What disadvantages Phylum Chlorophyta - Ulvophyceae – Ulva (sea lettuce) - Multicellular seaweed with flattenedgreen blades and basal holdfast to anchor blades to rocks • Haploidand diploid blades o Diploid blades produce spores that develop into haploid blades. o Haploid blades bear gametangia that form gametes. o Gametes fuse to form zygotes that grow into diploid blades. – Exhibit isomorphism- Haploidand diploid blades indistinguishable. Phylum Chlorophyta - Ulvophyceae • Ulothrix – Filamentous with holdfast cell at one end – Chloroplast - Wide, curved, somewhat flattened, with one to several pyrenoids – Asexual reproduction: • Cells contents condense, divide by mitosis and become zoospores inside parent cell. • Zoospores escape through pore in parent cell wall. – Resemble Chlamydomonas cells – Growinto new filaments Phylum Chlorophyta - Ulvophyceae v Ulothrix sexual reproduction: • Ulothrix – Cell contents condense and divide by mitosis inside parent cell. – Each new cell produces flagella. – Cells escape from parent cell and become gametes. Phylum Chlorophyta – Class in progress • Spirogyra (watersilk) – Filaments of cylindrical cells – Frequently floats in masses on surface of quiet freshwater – Chloroplast ribbon- shaped and spirally wrapped around vacuole, with pyrenoids at regular intervals. – Asexual reproduction: • Only by fragmentation of filament Phylum Chlorophyta • Spirogyra (watersilk) – Sexual reproduction by conjugation. • Papillae fuse and form conjugationtubes. • Condensed protoplast of one filament flows or crawls through tube to adjacentcell. • Protoplasts fuse,forming zygote thatdevelops thick wall. • Eventually zygoteundergoesmeiosis. Class Charophyceae • The Stoneworts – Shallow, freshwater lakes and ponds – Often precipitate calcium salts on their surfaces – Axis with short lateral branches in whorls. – Sexual reproductionis oogamous. – Multicellular antheridia – Transitional to terrestrial plants!! Which of the following is unicellular despite being a big organism? A. Acetobularia B. Chlamydomonas C. Volvox D. Chlorella E. Spirogyra Which of the following is unicellular despite being a big organism? A. Acetobularia B. Chlamydomonas C. Volvox D. Chlorella E. Spirogyra Plastid Kleptocracy Secondary and Tertiary Endosymbiosis Add a new membrane layer each tim !e You knew the concept for Exam I, now you need to know the groups!! From: http://www.nature.com/scitable/topicpage/the-origin-of-plastids-14125758 ? Stramenopila Alveolata Chlorophyta Phylum Stramenopila/Heterokonta • Yellow -green algae (Xanthophyceae) – Mostly freshwater, with a few marine and terrestrial representatives Stipitococcus, a • Two flagella of motile cells are yelalgaereen oriented in opposite directions. • Vaucheria - Oogamous, coenocytic, filamentous species – Aplanospores formed during asexual reproduction. – Sexual reproduction rare. Sexual reproduV aucheria Sea Slug Kleptoplasty • Sea slug – Animalia • E. chlorotica • Eats Vaulcheria algae • Sucks the chloroplasts out of the cell • They migrate into its cells – Thus the sea slug becomes a PHOTOSYNTHETIC ANIMAL • Chloroplasts are stable in a sea slug for up to a year (or more • Symbiosis/Endosymbiosis Phylum Stramenopila/Heterokonta • The Diatoms (Bacillariophyceae) – Unicellular – Fresh and salt water, particularly abundant in cold marine habitats – Also, dominate algal flora on damp cliffs, tree bark or buildings • Look like ornate, glass boxes with lids – As much as 95% of wall is silica. • Chlorophylls a and c and fucoxanthin • Food reserves - Oil, fats or laminarin Phylum Stramenopila/Heterokonta • The Diatoms (Bacillariophyceae) – Asexual reproduction results in half of cells becoming progressively smaller. – Original cell size restored through sexual reproduction. Phylum Stramenopila/Heterokonta • Brown algae (Phaeophyceae) – Relatively large; none unicellular or colonial – Most marine; majority in cold, shallow water – Many have a thallus differentiated into a holdfast, a stipe, and blades. • Blades may have gas-filled bladders. – Chlorophylls a and c, fucoxanthin – Food reserve = laminarin – Algin in cell walls. Nereocystis, a kelp Phylum Stramenopila/Heterokonta • Brown algae (Phaeophyceae) – Sargassum - Floating brown seaweed – Asexual reproduction by fragmentation or autospores. Sargassum Phylum Stramenopila/Heterokonta v Brown algae (Phaeophyceae) • Fucus - Common rockweed • Sexual reproduction: – Receptacles at tips of branches contain spherical chambers called conceptacles with gametangia inside. » Oogonium produces 8 eggs. » Antheridium produces 64 sperm. – Eggs and sperm released into water. Phylum Heterokontophyta/Alveolata • The Dinoflagellates – Red tides- Sudden multiplication of dinoflagellates • Some produce neurotoxins that accumulate in shell fish. – Cellulose “armor plates ” inside cell membrane – Two flagella in intersecting grooves • One trails behind cell - Acts as rudder – Other encircles cell at right angles - Gives cell spinning motion Phylum Heterokontophyta/Alveolata • The Dinoflagellates – Most have disc-shaped chloroplasts. • Contain xanthophyll pigments • Chlorophylls a and c – About 45% nonphotosynthetic – Chromosomes remain condensedand visible throughoutlife of cell. – Starch food reserve – Many have tiny projectiles that fire when irritated. – Dinoflaggelatesare in the SAR group • Only photosynthetic through secondary and tertiary endosymbiosis Phylum Heterokontophyta/Alveolata • Dinoflagellate trouble… – The red tides kill millions of fish by O2consumption when decaying in fresh Fish kill by algal bloom water – Some produce neurotoxins (brevetoxin) that are transferred to humans in shellfish – Some lodge into the fish gills and suffocate them. Non-toxic Chaetocerosknocks fish out by attaching to the gills by appendages Phylum Euglenophyta • The Euglenoids – No cell wall; pellicle = plasma membrane and underlying strips that spiral around cell • Flagellum pulls cell through water. • Gullet ingests food. • About 1/3 of species have disc- shaped chloroplasts. • Red eyespot for light detection • Paramylon food reserve • Asexual reproduction by cell division. • Sexual reproduction not confirmed. • Chloroplast may have been independently acquired • Chloroplast is dispensible • Remember endosymbiosis Phylum Cryptophyta • The Cryptomonads – Marine and freshwater – Two flagella – Plates on inside of plasma membrane – Single, two-lobed chloroplast with starch granules surrounding a central pyrenoid – Nucleomorph - Vestigial nucleus of primitive symbiotic organism – Gullet lined with ejectosomes. – Sexual reproduction Multicellular Evolution Primary Source: JT Bonner , “First Signals” Chapter 2, available on KSOL Additional sources: Hickman 3, 5 and 6; Bidlack4 Objectives • Understand in which domains multicellularity evolved • Understand the ecological pressures that lead to multicellular evolution • Understand the three mechanistic theories of multicellular evolution • Understand example organisms that are classical multicellular model systems and/or organisms that are transitional multicellular – Name the species and its domain – Name the mode of multicellular evolution How many times have multicellular organisms evolved? A. 1 B. 2 C. 10 D. 25 Protists Protozoa Do not exist as a phylogenetic distinct group This is a catch all category for single celled stuff found in water that is hard to classify without genomic data. Multicellular eukaryotes evolved in ≥25 times independently From Nicole King, Dev. Cell 7 313-25(2004) Cells exist in a very narrow range of sizes: Why? Typical Un-reinforced cell sizes The fundamental problem: How to get bigger without bursting the membranes 3500000 3000000 e2500000 c2000000 Cell Surface Area: 4*π*r 2 r 1500000 e C1000000 500000 Cells can double in size over 0 1 10 100 1000 10000 ~100x size range without log(Cell Volume) significant increases in cell surface area 3 Cell Volume 4/3*π*r A tangible example: Bubbles Large bubbles are very fragile Groups of small bubbles are more stable and strong Why get bigger? Competition for limited resources – natural selection for being bigger Recall resource limitation and natural selection limits organism growth A second fundamental problem: How to concentrate resources Differentiating tissues allow metabolic flexibility, but without being One metabolism type connected there is no advantage Coming together as Differentiating a multicellular tissues allow organism metabolic flexibility, concentrates AND the ability to resources concentrate resources A third fundamental problem: How NOT to be lunch Being bigger resists the wrath of predators! Three Non-exclusive Theories of Multicellular Evolution • Symbiosis – Two un-like organisms form a symbiotic relationship ultimately leading to the evolution of a multicellular organism – Also known as co -evolution – Few direct examples, but endosymbiosis was a key event allowing Eukaryotes to transition from mostly unicellular to large differentiated multicellular organisms • Aggregative Cooperation – Like symbiosis, but with two of the same species – Complex to evolved • Cellularization – A single cell undergoes incomplete cell division, mitotic (or meiotic) products stay together – The simplest to evolve – Probably the most common mechanism of multicellular evolution Bacterial Examples of Multicellularity • Myxobacteria(slime bacteria) – Domain Bacteria, Phylum proteobacteria, Class Delt- proteobacteria, Order Myxococcales – Chondromycescrocatus • Rod shaped unicells • When nutrients are limiting aggregate and form fruiting bodies • Some cells form stalk • Some cells sporulate, stalk elevates cells to promote dispersal – Which multicellularity theories apply? • Aggregative cooperation Bacterial Examples of Multicellularity • Cyanobacteria – Anabaena • Domain Bacteria, Phylum Cyanobacteria, Order Nostocales Heterocyst • Long chains of like cells • Arise by incomplete fission • Vegetative cells perform oxygenic photosynthesis • Some cells can differentiate into heterocysts . – Anoxic – Nitrogen fixation in differentiated tissue because, – Nitrogen fixation is O2 sensitive – Which multicellularity theories apply? • Cellularization Bacterial Examples of Multicellularity • Actinomycetes – Streptomyces – Domain Bacteria, Phylum Actinobacteria, ClasActinobacteria • Filamentous • Produces aerial hyphae • Look like mold • Like all Actinobacteria often found in soil and decomposing material • Many antibiotics are produced by these species • Tetracyclin, Streptomycin, Chlorampnenicol – Which multicellularity theories apply? • Cellularization Archaeal Examples of Multicellularity • Methanosarcina – Domain Archaea, Phylum Euryarchaeota, Class Methanomicrobia • Anaerobic • Makes methane gas • Grow in extreme environments • Grow as colonies • Mechanisms to keep O2 out of the inside of the cells? – Which multicellularity theories apply? • Cellularization Volvocine algae • Domain Eukaryote, Kingdom Plantae, Phylum Chlorophyta • Closely related species ranging from unicellular (Chlamydomonas ), to colonial multicellula (onium), to cel- type specification (Pleodorina) to Germa-soma specialization (Volvox ) • Chlamydomonasand Volvoxhave nearly identical genomes • ~35 genes different, ~6-8 genes unique to Volvox • Even though they are algae, the biology of green algae is more similar to animals • Volvocine algae are NOT the ancestors or land plants • Which multicellularity theories appl? y • Cellularization Chlamydomonas Gonium Eudorina Pleodorina Volvox Unicellular Colonial ECM expansion Cell type specificationifferentiated tissues multicellular multicellular multicellular Germ/Soma multicellular ~<200 Ma Eukaryotic Examples of Multicellularity Cellular slime molds Dictyostelium discoideum – Domain Eukarya, Kingdom Amoebozoa, Superphylum Conosa, Phylum Mycetoza, ClassD ictyostelia – Look like mushrooms, but are NOT fungi – Social amoeba – Only unicellular amoeba reproduce sexually (very limited) – Unicellular • Unicells free from each other • Grow and divide asexually – Stress causes multicellular induction • Separate organisms aggregate • Form a mobile slug stage • Differentiate into a fruiting body – Which multicellularity theories apply? • Aggregative cooperation Eukaryotic Examples of Multicellularity • Trueslime molds • Myxomycetes – Domain Eukarya, Kingdom Amoebozoa, Phylum Mycetoza – Look like mushrooms, but are NOT fungi – Amoeba – Growth stage is as a zygote • Multiple nuclei • Single cell, not social! – Stress causes gametogenesis • Form stalks and fruiting bodies • Spores then dissipate – Which multicellularity theories apply? • Cellularization • Aggregative cooperation Eukaryotic Examples of Multicellularity • Choanoflaggelates and Sponges – Monosigabrevicollic (Choanoflaggelate ) • Domain Eukarya, Kingdom Opisthokonta, Phylum Choanozoa • Unicellular flaggelates • Range of species from unicellular to colonial multicelular – E.g. Proterospongia • Some are facultative colonial • Earliest known species with a common ancestor to Metazoans (animals) • Have small gene family of Cadherins – Proteins that allow cells to adhere Eukaryotic Examples of Multicellularity Sponges • Domain Eukarya, Phylum Porifera, • Parazoans: Sponges and placozoans (1 sp.) • Sponges evolved from a species with a common ancestor with choanoflagellates • Simplest multicellular animals • Cellular organization: specialized cells without tissues Types of Cells in Sponges Choanocytes = flagellated,line canals Pinacocytes = protective outer covering Porocytes = tubes for water flow Archaeocytes = amoeboid for phagocytosis, other types secrete skeletal components Multicellularity Can Be Evolved in the Lab Ratcliff et al 2012 PNAS How hard is it to evolve 14t isolate 100 µm 60t isolate multicellularity? 14 60 C D Uni- transfers transfers • Approach: Use centrifugation ancestor 40 to select for larger yeast cells • Centrifugation is not 30 ecologically relevant, but their experimental setup is for a 2 2 20 strong selective pressure 8·10 • Do the cells become bigger, or do they become multicellular? 2 10 4·10 Offspring size • After 14 transfers (14 days!!!) (% of parent size) multicellular yeast appear 0 • After 60 transfers (60 days!!!) Clustersizeat 14 60 multicellular yeast dominate reproduction (µm ) transfers Untreated Genotype Fig. 6. High rates of apoptosis evolve, decreasing propagule size. (A and B) High rates of apoptosis evolve between transfers 14 and 60 in replicate The multicellular yeast cells form a “snowflake” morphology A single progenitor cell initiates a new colony that then grows outward They observe that the snowflakes have “holes” in them What might be causing the holes within the “snowflake” morphology? Ratcliff et al 2012 PNAS Some cells in the aggregates undergo programmed cell death (colored cells in micrographs) Thus, the authors observed division of labor (first step toward differentiated tissues) was observed In other words, cells within the cluster give up their reproduction, for the survival of their clonal neighbors! A B 14t isolate 100 µm 60t isolate 100 µm C D Uni- 14 60 cellular ettransfersPNtransfers This should blow your mind Acan occur IN THE LAB in a short amount of ity time. reproductive potential for the good of the colony! On your own • Place these species on to the tree of life • Compare and contrast the life cycles of these organisms • What ecological pressures might have led to the evolution of these multicellular examples Both Dictyostelium and Myxomycetes A. Life cycles are identical because they look the same B. Have completely different life cycles C. Have different life cycles, that evolved from a recent ancestor that had similar life cycle aspects of both D. Have weird names that I can’t even pronounce so their biology isn’t cool Prokaryotes Voyage of the Microbial Eukaryote From where they came Bidlack Chapter 17 Online Supplement Objectives • Think about what an organism concept is, especially in the microbial world (integrative theme!) • Describe the differences in cell architecture and cell function between Bacteria and Eukaryotes • Describe how the biology of Bacteria and Archaea are similar and different from that of Eukaryotes • Describe representative species, metabolism, morphology and lifestyle typical of these Bacteria – Actinobacteria – Firmicutes – Proteobacteria – Cyanobacteria – Chlorobacteria • Describe the type of environment where a typical Archaea would be found • Describe which domains contain photosynthetic organisms REQUIRED READING Introduction • Fossils of bacteria - 3.5 billion years old • Fossils of first eukaryotic cells - 1.3 billion years old • 5,000+ species of bacteria recognized today. – Each species found in astronomical numbers. • But, difficult to classify simple one-celled organisms, thus number of bacteria species uncertain. • Strains of one species look alike. – Clustered by what they do Features of Domains Bacteria andArchaea A quick review • All have prokaryotic cells. – No nuclear envelopes – Have long circular strand of DNA, ribosomes, membranes and plasmids – No membrane-bound organelles, such as plastids, mitochondria, golgi, endoplasmic reticulum – Bacteria and Archaea can be unicellular, multicellular or BOTH! Section of Prochloron cell Features of Bacteria and Archaea • Nutrition: – Primarilyby absorptionof food in solutionthrough cell wall – Perform a wide array chemical reactions or by photosynthesis • Reproductionpredominately asexual, by fission. – Fission- No mitosis, DNA strand duplicatesand is distributedto new cells. • No sexual reproduction – Genetic recombination facilitated bpili or by close contact of cells . – Bacteria are very promiscuous and share genetic elements readily. Features of Bacteria and Archaea Cellular Detail and Reproduction of Bacteria • Folds of plasma and other membranes perform some of functions of organelles in eukaryotic cells. • Ribosomes present, but about half the size as those of eukaryotic cells. • Nucleoid - Single chromosome in form of ring • 30 or 40 plasmids may be present. – Plasmids - Small circular DNA molecules that replicate independentlyof chromosome – Entire complement of plasmids consists of multiple copies of one or few different DNA molecules. Features of Bacteria and Archaea Cellular Detail and Reproduction of Bacteria • Mitosis does not occur. • Fission: – The two copies of duplicated chromosomes migrate to opposite ends of cell. – Perpendicular walls and cell membranes formed in middle of cell. – The 2 new cells separate and enlarge to original size. Replication of nucleoid Features Bacteria and Archaea Cellular Detail and Reproduction of Bacteria • Fission: – May undergo fission every 10 - 20 minutes under ideal conditions • Usually exhaust food supplies and accumulate wastes New wall growing inward of dividing bacterial cell Features of Bacteria and Archaea Cellular Detail and Reproduction of Bacteria • Do not produce gametes or zygotes, and do not undergo meiosis • Three Forms of Genetic Sharing: • Conjugation – DNA transferredfrom donor cell to recipient cellusually through pilus (pleural: pili). • Transformation – Living cell acquiresDNA fragments released by dead cells. • Transduction – DNA fragments carried from Conjugation one cell to another by viruses. Features of Bacteria and Archaea Size, Form, and Classification of Bacteria • Most bacteria less than 2 or 3 micrometers in diameter. • Occur primarily in three forms: Cocci Spirilla Bacilli Helix or spiral Spherical or Rod-shaped or elliptical cylindrical Features of Bacteria and Archaea Size, Form, and Classification of Bacteria • Also classified by: – Presence of sheath around cells, of hair-like or bud-like appendages,of endospores, of pili or of flagella – Color – Mechanisms of movement – Biochemical characteristics – Reaction of cell walls to dye • Gram-negative • Gram-positive Bacteria • True bacteria have muramic acid in cell walls, and are different fromArchaea in their RNA bases, metabolism and lipids. • Bacteriophyta – Not used in the 3-domain system • Unpigmented, purple, and green sulfur bacteria • Bacteria are either – Heterotrophic - Cannotsynthesizeown food » Majority saprobes - Foodfrom nonlivingorganic matter • Responsiblefor decayand recycling of organic matter in soil » Some parasites - Dependon living organismsfor food –substancesic - Synthesizeorganic compoundsfrom simple inorganic » Photosynthetic » Chemotrophic Firmicutes Chloroflexi Cyanobacteria Actinobacteria Proteobacteria Chlorobi Phylum Firmicutes Gram Positive Bacteria • Firma = strong; cutis = skin • Most gram-positive • Many well known pathogenic and beneficial species • Firmicutesare both beneficial and harmful – Largest portion of your gut m icrobiomehas Firmicutes species • 1) Class Bacilli, orderB acillales – Genus Bacillus • Obligate aerobes or facultative aerobes • Found almost everywhere in nature • Form endospores when stressed • Bacillus subtillis –one of the best studied model prokaryotes • extremely toughcis –causes anthrax. Anthrax endospores are • Bacillus thuringenesis –produces a toxin that kill insects – B. thuringenesis can be applied directly to crops and kills a wide array of insects – plants. Makes them resistant to insect pestsesis and transformed into • Class Bacilli, order Bacillales – Genus Listeria • Gram positive • Listeria monocytogenes – Causes food borne illness – Extremely serious with a 20%+ mortality rate – Causes sepsis and meningitis – Phagocyticallyup taken into cells and hijack thr tinomyosin transport machinery to move between cells – Move by flagellar motility outside cells – If found in a food plant it requires complete shutdown, sanitation and testing. Often more cost effective to build a new plant! – Genus Staphylococcus • Gram positive • Found all over our environment – most harmless • Can be pathogenic in some circumstances • Overuse of antibiotics has causes the evolution of an opportunistic pathogenic strain of S. aureus that is resistant to almost all known antibiotics –MRSA, Vancomycinresistant S. aureus – Mintroduced into tissues via surgery, catheters, respiratorsogenic when – MAJOR public health problem in hospitals. – Mhand washing found on hospital surfaces, significant effort being put into – Now becoming a significant problem with those that handle livestock • Class Bacilli, order Bacillales – Genus Lactobacillus • Gram positive • Facultative anaerobe • Break down sugar into lactic acid • Used in the production of yogurt and cheese and other food products • Organism that is thought to promote healthy digestion - probiotic • Symbiotic Lactobacillus and yeast make sourdough bread • Class Bacilli, order Clostridia – Genus Clostri
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