Protists and Viruses
Protists and Viruses BSC 1011C
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This 84 page Class Notes was uploaded by Laura Notetaker on Friday December 11, 2015. The Class Notes belongs to BSC 1011C at University of North Florida taught by Amy Keagy in Fall 2015. Since its upload, it has received 13 views. For similar materials see General Biology II in Biology at University of North Florida.
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Date Created: 12/11/15
Single cell with many nuclei 1 cm Chapter 29 - Protists Protists – “Simple” eukaryotes – Mostly unicellular – Some form colonies – Some are coenocytic • Multiple nuclei in one mass of cytoplasm – A few are multicellular • Important in the biosphere – Food for other organisms – Photosynthetic protists supply oxygen • Seven major lineages Trichonympha of eukaryotes always changing, still paraphyletic General Biology of the Protists Cell surface -Plasma membrane -Cell walls (in some) -Extracellular material (ECM) (in some) -Calcium or silica shells Cysts -Dormant cell with resistant outer covering -Used for disease transmission General Biology of the Protists Locomotion -Flagella -Cilia -Pseudopodia (“false feet”) -Lobopods – Large, blunt -Filopods – Thin, branching (a) Swimming via flagella (b) Swimming via cilia General Biology of the Protists Nutrition -Phototrophs -Heterotrophs -Phagotrophs – Particulate food matter -Osmotrophs – Soluble food matter phototrophic andboth heterotrophic General Biology of the Protists Asexual reproduction -Typical mode of reproduction -Some species have an unusual mitosis -Binary fission = Equal cells -Budding = Progeny cell smaller -Schizogony = Multiple fission Sexual reproduction -Union of haploid gametes which are produced by meiosis • Physarum.MOV What is this organism? Is it unicellular? Multicellular? Is is a heterotroph or autotroph? What phenomenon is occurring in this video? Check out these links for protist images: •http://www.biology.ualberta.ca/courses.hp/zool250/Labs/Lab02/Lab02.htm •http://ww2.manson.org/pauly/Biology/Online%20assignments/Protist%20Lab.htm •http://www.seaweed.ie/algae/chlorophyta.html Bacteria This icon shows the overall Archaea tree of life. The highlighted EUKARYA branch indicates which lineage is shown in more detail below Bacteria Archaea EUKARYA Fungi Animals All eukaryotes are protists (orange branches) except for the Common fungi, animals, ancestor of all and land plants eukaryotes Land plants 1. Ancestor of eukaryotes. Chromosomes Plasma membrane 2. Infoldings of membrane. 3. Eukaryotic cell. Nucleus Endoplasmic reticulum Aerobic bacterium Anaerobic eukaryote Nucleus 1. Eukaryote cell engulfs bacterium. 2. Bacterium survives. 3. Endosymbiosis: Both benefit. Predatory protist Photosynthetic protist Nucleus Chloroplast Nucleus 1. Photosynthetic protist is engulfed. 2. Nucleus from photosynthetic protist is lost. Organelle with four membranes 4 1 2 3 How are protists involved in the environment? “Plankton” Primary Producers inAquatic Food Chain 0.5 mm 5 cm Open ocean: Surface waters teem Shallow coastal waters: GiganticIntertidal habitats: Protists such as with microscopic protists, such aprotists, such as these kelp, fothese red algae are particularly these diatoms. underwater forests. abundant in tidal habitats. Figure 29-3 Slide 7 Haploid (n) MITOSIS Cell type Diploid (2n) present in Mosquito (n) mosquito bite saliva that (n) infects Infection of liver cells in human humans Human host Mosquito host Male gamete (n) Cell types Mosquito present in Oocyst bite human blood (2n) Female that infect gamete (n) mosquitoes 20 m Arrows indicate movement of carbon atoms Primary producers Primary consumers Decomposers and scavengers Sinking Sinking Sinking Dead cells and CaCO 3hells accumulate on bottom Bacteria Archaea Meanings of the names for the AMOEBLobose amoebae Cellular slime molds 7 eukaryotic Lineages: UNIKONTA Plasmodial slime molds 1) Amoebozoa: move with OPISTHOKONTA Fungi “amoeboid” motion Choanoflagellates All eukaryotes Animals are protists 2) Opisthokonta: “rear flagellum” except for the EXCAVATA fungi, animals, Parabasilids EUKARYOTES and land plants 3) Excavata: “excavated” feeding Diplomonads Euglenids groove on outside of cells Kinetoplastids PLANTAE 4) Plantae: “plants” Glaucophyte algae Red algae 5) Rhizaria: “root-like” Green algaeGreen plants BIKONTA pseudopods Land plants RHIZARIA Foraminifera 6) Alveolata: “alveoli” on their cell Chlorarachniophytes membranes ALVEOLATA Ciliates CHROMALVEOLATA 7) Stramenopila: “hairy flagella” Dinoflagellates Apicomplexa STRAMENOPILA Oomycetes Diatoms Brown algae Lineage: Amoebozoa Amoebas & Slime Molds Amoeboid motion via pseudopodia (a) Amoebas use pseudopodia to engulf food Protist Prey 1 m Pseudopodium 2 TYPES of SLIME MOLDS 1. Plasmodial slime molds -Stream along as a plasmodium, a nonwalled, multinucleate mass of cytoplasm -Ingests bacteria and other organic material -When food or moisture is scarce, organism forms sporangia, where spores are produced Physarum polycephalum Single cell with many nuclei 1 cm 2. Cellular slime molds -Individual organisms behave as separate amoebas -Move through soil ingesting bacteria -When food is scarce, organisms aggregate to form a slug -Slug differentiates into a sorocarp 311644 Credit: © Carolina Biological/Visuals Unlimited Slime Mold (Dictyostelium discoideum) aggregation stag. 311699 Credit: © Carolina Biological/Visuals Unlimited Slime Mold (Dictyostelium discoideum) slug stag. Lineage: Opisthokonta • Fungi • Choanoflagellates • Animals Lineage: Excavata • Parabasalids • Diplomonads • Euglenids • Kinetoplastids Diplomonads -Have two nuclei -Giardia intestinalis Parabasalids -Have undulating membranes -Trichonypha Trichomonas vaginalis Cluster of flagella Rod of microtubules 5 m Giardia lamblia Flagella Two nuclei 5 m Plant-like, or Animal-like? Euglenozoa Euglenoids were among the earliest eukaryotes to possess mitochondria -1/3 have chloroplasts -All have a flexible pellicle -None have sexual reproduction Euglenozoa Euglena velata Eyespot Chloroplasts Flagellum 10 m Euglenozoa Kinetoplastids -Unique, single mitochondrion with DNA maxicircles and minicircles (RNA editing) -Trypanosomes cause human diseases -African sleeping sickness – Tsetse fly -Leishmaniasis – Sand fly -Difficult to control because organisms repeatedly change their protective coat Euglenozoa Lineage: Plantae •Glaucophyte algae •Red algae •Green algae •Plants Chara – commonly called stonewort. This green alga is Ulva – sea lettuce closely related to land plants. (a) Alternation of generations in which multicellular haploid and diploid forms look identical (Ectocarpus siliculosus) Male and female gametophytes Meiosis occurs in are separate specialized structures Spores (n) Gametes are produced by mitosis in Gametophytes (n) specialized structures Gametes Sperm Sporophyte (n) Egg (2n) Haploid (n) Diploid (2n) Zygote germinates and Zygote grows into sporophyte (2n) (b) Alternation of generations in which multicellular haploid and diploid forms look different (Laminaria solidungula) Meiosis occurs in specialized structures Male and female gametophytes are separate Spores (n) Gametophytes (n) Sperm Sporophyte Egg (2n) Zygote (2n) Green Algae • diverse in size, structural complexity, and reproduction – May be the ancestors of land plants • Charophytes – Multicellular forms do not have cells differentiated into tissues, unlike plants – Chlorophylls a and b and carotenoids present in chloroplasts. – Have haploid and diploid life generations. – Plants have adaptations for terrestrial life Spirogyra 25 µm 100 µm Desmid-unicellular green Volvox-colonies of up algae with mirror halves. to 50,000 cells. RedAlgae •Ecologically important in warm waters •Contain Floridean starch •Red algae range from microscopic to very large sizes •Lack flagella and centrioles •Have unique accessory photosynthetic pigment (phycoerythrin) within phycobilisomes •Origin has been a source of controversy •Tentatively, treated as a sister clade Chlorophyta (green algae) 1 cm Lineage: Rhizaria • Foraminifera • Chlorarachniophytes Unidentified species 0.1 mm Lineage: Alveolata • Ciliates • Dinoflagellates • Apicomplexa (a) Ciliary currents sweep food into gullet Cilia Fish and harm swimmersoms produce toxins that kill Gullet Paramecium caudatum Cilia Micronucleus Macronucleus 50 m Dinoflagellate Noctiluca scintillans Light produced by cells 0.5 mm Apicomplexa -Apical complex is a unique arrangement of organelles at one end of the cell -Enables the cell to invade its host -Spore-forming animal parasites -Plasmodium and Toxoplasma Plasmodium Plasmodium -An apicomplexan that causes malaria -Eradication of malaria 1. Elimination of mosquito vectors 2. Development of drugs 3. Development of vaccines -Organism has a very complex life cycle Toxoplasma gondii -Causes infections in humans with immunosuppression Toxoplasma gondii Toxoplasma cells Human cell 5 m Lineage: Stramenopila • Oomycetes • Diatoms • Brown algae Phytophthora infestans Oomycetes Structures that produce spores Known as water molds, have hyphae and reproduce with spores -Irish potato famine caused by Phytophthora Potato leaf infestans -Fish disease “ich” caused by Saprolegnia 50 m Diatoms • Unicellular organisms - • Have unique cell wall made of silica called a frustule • Some move using raphes • Two long grooves lined with vibrating fibrils • Photopigments are primarily carotenoids • Frustules used as abrasives in many cleaning products and to control insect pests. Brown Algae -Kelps throughout the worldshallow waters -Pigments include fucoxanthin – Multicellular seaweeds – Ecologically important in cooler ocean waters – Kelps have leaflike blades, stemlike stipes, anchoring holdfasts, gas-filled bladders – Algin – ice cream, toothpaste, shaving cream, hair spray, hand lotion -Life cycle involves alternation of generations Air bladders Blade Stipe Sargassum sp. Holdfast Postelsia species Unikonta = (1 flagellum)Amoebozoa & Opisthokonta Bikonta =(2 flagella) all other lineages (a) Diatom (b) Dinoflagellate (c) Foraminiferan 50 m 10 m 50 m Glassy cell wall made of silicon Tough plates in cell wall made of Chalky, chambered shell made of calcium dioxide cellulose carbonate Viruses Chapter 35 Characteristics of Viruses A. Definition: obligate intracellular parasite 1. Requires a host cell for replication 2. Reproduces at the expense of the host cell 2 Characteristics of Viruses B. Nonliving “particles” called virions 1. Nucleic acid core surrounded by a protein capsule called a capsid a. Enveloped or nonenveloped b. Classified by genome i. RNA or DNA ii. SS or DS iii. Positive, negative, or ambisense 3 2. Unique shape a. Rods b. Polyhedrons c. Spheres d. bacteriophages 4 3. Vary greatly in size 20-300nm 5 6 4. Host specific “strains” Viruses are obligate intracellular parasites -Host range = Types of organisms infected -Tissue tropism = Types of cells infected Viruses can remain dormant or latent for years More kinds of viruses exist than organisms 7 5. Viral Replication Viruses can only reproduce inside cells -Outside, they are metabolically inert virions Virus hijacks the cell’s transcription and translation machineries for the assembly and release of more viruses 6. Able to evolve 8 7. No metabolism No amino acid or protein synthesis No ATP formation 9 II. Role in Environment A. Cause Damage and Death to cells - - organisms (virulent, emerging diseases) B. Pandemics - - epidemics - - world wide concern - 28 million deaths so far AIDS - 33 million currently infected 10 Human Immunodeficiency Virus HIV causes acquired immune deficiency syndrome (AIDS) AIDS was first reported in the US in 1981 Some people are resistant to HIV infection -Have mutation in the CCR5 gene -Encodes a receptor for HIV -Also for the smallpox virus 11 Human Immunodeficiency Virus HIV targets CD4 cells, mainly helper T cells -Without these cells, the body cannot mount an effective immune response -Host may ultimately die from a variety of opportunistic infections Tests for HIV detect anti-HIV antibodies -Not circulating viruses 12 Life cycle of HIV 13 III. Cycle of a Viral Infection Bacteriophage = bacteria “eater” Exhibit two reproductive cycles (other viruses usually exhibit a variation of one of these) A. Lytic cycle = Virus kills the host cell incorporates into the cell’s genome Lytic phages are called virulent Lysogenic phages are called temperate Manlytic. Referred to as inductionenic to 14 A. Lytic cycle 1. Destroys the host cell • Attachment (Adsorption) • Penetration • Replication (Synthesis) • Assembly • Release 2. Replicative growth 3. Cells machinery is hijacked 15 B. Lysogenic cycle 1. Usually does not kill the host 2. No new virions 3. Viral genome replicated along with host DNA • Attachment • Penetration • Integration • Replication (Propagation) 16 C. Factors Affecting Viral Infection 1. Enter cells by directly injecting genetic material or by binding to specific membrane molecules (fusion) 2. Lysozymes degrade bacteria cell wals 3. Proteins made by ribosomes on ER or by ribosomes in cytoplasm 17 4. DNA/RNA synthesis a. Viral DNA polymerase b. RNA replicase c. Reverse transcriptase (retroviruses) RNA ss cDNA ds cDNA 5. Vaccines 18 IV. Origins of Viruses 3 Hypotheses “degenerates” • Plasmids • Symbionts of Bacteria • Early RNA based life forms 19 Prions “Proteinaceous infectious particles” Cause transmissible spongiform encephalopathies (TSEs) -Mad cow disease -Scrapie in sheep -Creutzfeldt-Jacob disease in humans Animals have normal prion proteins-Misfolded proteins cause disease 20 Viroids Tiny naked molecules of circular RNA -Cause diseases in plants ie. Coconuts,Potato spindle tuber viriod It is unclear how they cause disease 21