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Presentation on theme: "Microorganisms."— Presentation transcript:

1 Microorganisms

2 Viruses Biological particle composed of genetic material and protein Cause diseases Virulent –immediate Temperate - not immediately Obligate Parasite - only reproduces in a living host

3 Viruses Comparison with cells Constructed of compounds usually associated with cells Have some characteristics of life but not all No nucleus, cytoplasm, organelles, or cell membrane Don't reproduce by either mitosis or meiosis. Not capable of carrying out cellular functions Contain nucleic acids Can crystallize where cells cannot.

4 Viruses Viral Structure Core of nucleic acid - either RNA or DNA
Core surrounded by protein layer called Capsid Made of repeating protein units called Capsomeres   Gives virus its shape.   Function of viral nucleic acid   Codes for production of viral nucleic acid.   Control manufacture protein coat.   Shape   Icosahedron - 20 triangular faces; Most common shape Polio, chicken pox, colds   Helix - subunits of coat form spiral chain - like coiled spring Rabies, mumps   Strands surrounded by 2 protein layers - inner protein layer surrounded by lipid layer with embedded glycoproteins HIV.  

5 Viruses

6 Viruses Classification Major division RNA Viruses DNA Viruses
Lower levels based on shape and size.   Retroviruses - contains enzyme Reverse Transcriptase Directs host cell to make DNA using viral RNA of virus as a template.   Disease causing particles - smaller and simpler than virus   Viroid - short, single strand of RNA with no capsid interferes with normal cell functions   Prion - glycoprotein particle contains polypeptide of about 250 amino acids - no nucleic acid.  

7 Viruses Bacteriophage(Phage) - virus that infects bacteria
Have been used to gather information about viral replication.   Have round, oval, or many sided heads and hollow tails   Head contains nucleic acid.   Tail has fibers at tip Anchors phage to bacteria

8 Viruses

9 Viruses Lytic Cycle - fundamental reproductive process of viruses Consists of 5 phases. Attachment Entry Replication Assembly Release

10 Viruses

11 Viruses Lysogenic Cycle Involves temperate viruses
Viruses enter cell similar to lytic cycle Consists of a small segment of DNA Prophage   Viral DNA becomes additional set of genes Incorporates into host's DNA Replicates with host DNA   External stimulus - radiation, chemicals - cause prophage to become virulent  

12 Viruses

13 Viruses Evolution Believed to have evolved after cells
May be simplification of some existing cells.

14 Kingdoms Eubacteria and Archaebacteria
Most common members - bacteria Bacteria Characteristics   Prokaryotic - no nucleus Microscopic   Heterotrophs or autotrophs   Evolution   Fossil monerans billion years old.   Evolved into many forms - live in different environments.   Classification difficult; rely on physiology  

15 Kingdoms Eubacteria and Archaebacteria
Classification - 2 Kingdoms Kingdom Archaebacteria   Kingdom Eubacteria  

16 Kingdom Archaebacteria
 Adapted to harsh environments   Include methanogens, extreme halophiles, and thermoacidophiles.   Methanogens Anaerobic Use carbon dioxide and hydrogen to form methane Live in bog and lake bottoms, digestive tracts of livestock, and sewerage treatment plants.   Halophiles - live in high salt areas   Thermoacidophiles - live in very acidic and hot areas  

17 Kingdom Archaebacteria

18 Kingdom Eubacteria All members of which we commonly call Bacteria Identification Classified on basis of shape Coccus - spherical shaped cells Bacillus - Rod shaped cells Spirillum - Shaped like coiled rods or corkscrews Cells can cluster together or form chains or filaments Staphylo - cluster Strepto -filament Diplo - pairs Classified on reaction to Gram stain - stains pink or purple Gram-Negative - pink - difficult to treat with antibiotics Gram-Positive - purple -treated with antibiotics

19 Kingdom Eubacteria

20 Kingdom Eubacteria Two specialized Phyla Phylum Cyanophyta
Blue-green bacteria (algae) Similar to plants and plant-like protists Photosynthetic - produce food and oxygen. Clump to form colonies Exhibit some division of labor Phylum Prochlorophyta Photosynthetic Live symbiotically with tunicates Chlorophyll similar to eukaryotes.

21 Biology of Bacteria Structure and Movement
DNA arranged in single circular chromosome  called plasmids Cell walls differ from eukaryotes - some rigid, others flexible   Many produce Capsule - protective polysaccharide layer.   Glycocalyx - polysaccharide that helps many stick to surfaces Pili - Protein strands to attach themselves to objects   May form endospores under adverse conditions Permits bacteria to lie dormant for years.   Favorable conditions, endospore breaks; cell becomes active.   Movement   Many move by rotating stiff flagellum bent into S-curve.   Spirochetes use filament that wraps around cell to move  

22 Biology of Bacteria

23 Biology of Bacteria Nutrition May be heterotrophic or autotrophic Most are Heterotrophic Saprophyte feeds on dead or decaying matter. Parasite feeds on living materials Some Autotrophic Photoautotrophs - use sunlight as energy source. Chemoautotrophs - use energy of chemical reactions to synthesize food. Nitrogen Fixation - gaseous nitrogen converted into ammonia compounds

24 Biology of Bacteria Respiration
Obligate Anaerobes - cannot survive in presence of oxygen.   Facultative Anaerobes - can live with or without oxygen.   Obligate Aerobes - cannot live without oxygen.  

25 Biology of Bacteria Reproduction
Some reproduce rapidly - divide every minutes   Binary Fission - cell reproduces by splitting in two   Asexual   DNA replicates first   Plasma membrane and cell wall grows inward form 2 identical daughter cells.   Conjugation - type of sexual reproduction, genetic material exchanged.   Recombination of genetic material by 2 bacteria   Portion of DNA from one cell passes across bridge formed by pili.    Recipient DNA destroyed and new DNA is substituted

26 Biology of Bacteria Toxin Production
Pathogen - any organism that causes disease.   Most bacterial diseases caused by toxins produced by bacteria.   Toxin - poisonous substance that disrupts metabolism of infected organism.   Endotoxin - pieces of cell wall of Gram-negative bacteria Symptoms - fever, weakness, and damage to circulatory system Example - Typhoid Fever.   Exotoxin - products of bacterial metabolism Secreted into area around bacteria Most potent poisons known Examples - Diphtheria and Botulism (food poisoning)  

27 Biology of Bacteria

28 Kingdom Protista Characteristics Eukaryotic - have true nucleus.
Eukaryotic - have true nucleus.   Most are unicellular but some live in colonies.   Does include some simple multicellular organisms - lack specialized tissues.   Some autotrophic; others heterotrophic.   Live in aquatic or moist environments.   Reproduce sexually and asexually.  

29 Kingdom Protista Organisms placed in this kingdom because they don't have characteristics of organisms in other kingdoms.   Separated into 3 broad groups.   Prototozoa - heterotrophic protists; "first animals"   Algae - autotrophic protists.   Unusual Protists - fungus like protists  

30 Protozoa General Characteristics Heterotrophic
Most are unicellular, some form colonies - most are microscopic.   Live freely or as parasites (in the intestines is common)   Many free living protozoans makeup zooplankton Unicellular, heterotrophic organisms that drift in water.   Parasitic forms cause disease  

31 Protozoa

32 Protozoa Most lack a protective outer covering - semipermeable cell membrane serves as boundary.   Most have physiological mechanism for monitoring and responding to environment.   Sense touch and chemical changes - will bypass noxious chemicals.   Eyespots (in some) - Localized region of pigment that detects changes in quality and quantity of light.   Classified into 4 phyla - based on mode of movement.   Phylum Sarcodina - move by pseudopodia   Phylum Ciliophora - move by cilia   Phylum Zoomastigina - move by flagella.   Phylum Sporozoa - immobile; parasites  

33 Sarcodina - Amoeba Most have flexible cell membrane; Some marine forms have calcium carbonate shells. Move by means of pseudopodia - Ameboid Movement   Pseudopodium - "False Foot" - cytoplasmic extension that functions in movement.   Cytoplasm has 2 regions   Ectoplasm   Endoplasm  Ameboid Movement - internal flow of cell contents.   Excess water excreted by Contractile Vacuole Ingest nutrients (food) by phagocytosis Undigested food and water excreted by Exocytosis Reproduce by Binary Fission - identical offspring.   Form Cysts - protective outer wall - when conditions are bad  

34 Sarcodina - Amoeba

35 Ciliophora - Paramecium
Move by Cilia - short, hairlike projections Paramecium has rigid protein covering called Pellicle - shaped like shoe sole. Has 2 kinds of nuclei   Macronucleus - large; control cell activities Micronucleus - small; involved in sexual reproduction   Foodgetting and Digestion   Food enters through funnel-like Oral Groove -.   Cilia sweeps food to Mouth Pore .   Mouth pore opens into a Gullet, forms food vacuoles Contents of vacuole digested and absorbed.   Indigestible matter in vacuole moves to the Anal Pore -eliminated.   Exhibit Avoidance Behavior - move away from harmful conditions Reproduction   Asexual - Binary Fission - macronucleus splits– one part to each daughter cell.   Sexual – Conjugation - involves 2 mating strains; (+) or (-)  

36 Ciliophora - Paramecium

37 Zoomastigina (Mastigophora)
Move by 1 or more long, whiplike Flagella   Many freeliving.   Some are parasitic Best known - Trypanosoma - African Sleeping Sickness Transmitted by tsetse fly - live in Africa  

38 Sporozoa All parasitic.
No means of locomotion - in body fluids of hosts.   Reproduce by spores.   Example - Plasmodium   Causes Malaria   Complex Life Cycle - in female Anophiles sp. - mosquito   Spores enter blood stream thru mosquito saliva   Spores reproduce asexually - infect red blood cells - rupture releasing toxin and more spores - causes chills and fever. Mosquito bites infected person some of cells ingested - become gametes - combine and divide - migrate to mosquito's salivary glands to begin cycle again.  

39 Sporozoa

40 Algae General Characteristics Eukaryotic, plantlike protists
Autotrophic protists - produce food by photosynthesis.   Most aquatic - terrestrial forms in moist situations.   Unicellular and multicellular forms (large forms discussed with plants)   Thallus - Body of an alga - unicellular, colonial, filamentous, or thalloid.   Phytoplankton - photosynthetic plankton   Provide food for numerous aquatic organisms   Generates great amounts of oxygen. Were classified in past as plants Gametes formed in unicellular gametangia, plant multicellular gametangia.   Classified into 4 phyla - based on color, food storage substances, and cell wall composition.   All contain chlorophyll a; usually have other forms of chlorophyll   Contain accessory pigments.  

41 Chlorophyta – “Green” Algae
Unicellular, colonial, filamentous, or thalloid   Most aquatic or moist terrestrial environments   Photosynthetic Pigments - Chlorophylls a and b; xanthophylls, carotenes   Food stored as starch.   Cell wall composition - Polysaccharide, sometimes cellulose   Importance - Believed to be ancestors of plants  

42 Chlorophyta – “Green” Algae

43 Chrysophyta – “Golden Brown” Algae
Mostly unicellular   Photosynthetic pigments - Chlorophylls a and c; Carotenes - fucoxanthin   Food stored as Chrysolaminarin - oily carbohydrate   Cell wall if present of cellulose, some contain silica   Most members are Diatoms   Marine and freshwater specimens   Have silica containing shells - highly ornamented, double walls.   Halves fit together like a box - half called Valve   Types   Centric Diatoms - circular or triangular valves - marine waters.   Pennate Diatoms - rectangular valves - freshwater ponds and lakes   Responsible for bulk of worldwide photosynthesis.   Diatom shells don't decompose - forms Diatomaceous Earth - abrasive - ingredient in detergents, paint removers, fertilizers, insulators, scouring powders.  

44 Chrysophyta – “Golden Brown” Algae

45 Pyrrophyta – “Fire” Algae
Most are marine; oceanic phytoplankton - called Dinoflagellates - all unicellular   Photosynthetic pigments - chlorophylls a and c; Carotene   Food stored as starch   Cell wall of cellulose - looks like armor.   responsible for Bioluminescence - light produced by living things.   Produce "Red Tides" - discoloration of ocean ; population explosion of dinoflagellates - produce toxins may cause respiratory paralysis in vertebrates  

46 Pyrrophyta – “Fire” Algae

47 Euglenophyta – “True Eye” Algae
Have characteristics of green algae and protozoa. Contain chlorophylls a and b, carotenes in some. Food stored as a starch - Paramylon Have no cell wall, surrounded by pellicle Not completely autotrophic, heterotrophic - in the dark. Mostly freshwater species. Contractile vacuole gets rid of excess water. Moves by whipping flagellum.   Red-orange eyespot functions as light detector

48 Euglenophyta – “True Eye” Algae

49 Fungus Like Protists Members of group traditionally classified as fungi - actually are protists Life cycles look fungus like   Store food as glycogen Morphological differences considered superficial  

50 Fungus Like Protists Phylum Acrasiomycota - Slime Molds
Live mostly on land or in freshwater.   Feeding stage - Myxameba - uninucleate cell   Live on forest floor or on decaying plants   Move and feed like amoeba   During environmental stress myxameba come together to form a Pseudoplasmodium   Group of individual cells that act as one unit  Moves together.   Unit forms sporangia that produce spores   Spores develop into individual myxameba  

51 Fungus Like Protists

52 Fungus Like Protists Phylum Myxomycota - Plasmodial Slime Molds
Feeding stage - Plasmosium - multinucleate cytoplasm surrounded by a membrane that moves as a mass, feeds on organic matter   Stressful periods - plasmodium becomes stationary - produces sporangia on stalks   Sporangia produce spores - may be dormant for years.   Spore releases myxameba or flagellate swarm cells   Cells fuse; nucleus for zygote divides repeatedly   Doesn't undergo cytokinesis Multinucleate plasmodium  

53 Fungus Like Protists

54 Kingdom Fungi Diverse group living in many different habitats.
Characteristics   Eukaryotic   Many microscopic; some easy to see.   Important as decomposers - breakdown organic materials   Release inorganic materials to environment to be reused.   Most are either parasitic or saprophytic; a few predatory.   Parasite - organism that lives off of living organisms.   Saprophyte - organism that lives off of dead organisms or waste products.   Generally grow in moist environments.  

55 Kingdom Fungi Characteristics
Composed of vegetative filament called a Hypha - may or may not be divided by cross walls.   Coenocytic - filaments without crosswalls.   Hypha may be have perforated crosswall - Septum.   Hypha grows at tip.   Mycelium - a mat of interwoven hyphae.   Made of Chitin - complex polysaccharide, also in exoskeleton of arthropods and insects.   Food stored as glycogen.  

56 Kingdom Fungi Characteristics Reproduce both sexually and asexually.
Asexual Reproduction   Produce spores on special branches of hypha   Spores often carried by wind.   Finds suitable food source germinates; new hyphae grows  May reproduce asexually by fragmentation   Sexual Reproduction   Gametes from 2 mating strains undergo cytoplasmic fusion.   Nuclei don't fuse immediately - divide independently.   Heterokaryotic - different nuclei Homokaryotic - similar nuclei.

57 Kingdom Fungi Classification Basis Structure of hyphae
Coenocytic Hyphae – No crosswalls   Septate Hyphae - With crosswalls   Unicellular Hyphae - single cell   Type of Reproduction - particularly spore type.   Five Phyla   Phylum Oomycota   Phylum Zygomycota   Phylum Basidiomycota   Phylum Ascomycota   Phylum Deuteromycota  

58 Oomycota Aquatic and terrestrial species - water molds, white rusts, and downy mildews   Both parasitic and saprophytic   Coenocytic with branched hyphae   Cell walls have cellulose not chitin   Reproduction   Male gametangium, antheridium, release sperm   Female gametangium, oogonium, forms egg   Fusion of egg and sperm develops thick-walled diploid Oospore   Oospore germinates into coenocytic hyphae   Asexual reproduction - flagellated zoospores produce hyphae   Example - Phytophthora infestans   - Late Blight of Potatoes   Irish Potato Famine of   Result - mass migration of Irish to United States.  

59 Zygomycota – Rhizopus Bread Mold
terrestrial organisms   Coenocytic - hyphae lack septa   Reproductive structures are separated from other hyphae by unperforated cross walls   Rhizopus consists of 3 types of hyphae   Rhizoids - anchoring hyphae – absorb nutrients   Stolons - hyphae that grow across surface of bread   Sporangiophore - upright hyphae - sporangia at their tips   Reproduction   Asexual - spores from a sporangium on sporangiophore.   Sexual - Conjugation - two strains unite to form a Zygospore   Favorable conditions -asexual reproduction Unfavorable conditions - sexual reproduction

60 Zygomycota – Rhizopus Bread Mold

61 Basidiomycota – Club Fungi
Mushrooms, toadstools, puffballs, rusts, and smuts - mostly terrestrial Septate hyphae Underground hyphae produce Basidiocarp - reproductive body Mushroom is a basidiocarp. Stalk - stem-like portion Cap - flattened top portion Gills - radiating rows under cap - site of basidia; Basidium - club-shaped reproductive cell; produces Basidiospores Hyphae grows - septa form - called Primary Mycelium Hyphae grow,fuse with another mating strain – Secondary mycelium forms.   Hyphae heterokaryotic - one nucleus in each cell.   Secondary mycelium forms basidiocarp.   Asexual reproduction by fragmentation.   Importance   Rusts - parasites of many cereal crops   Smuts - plant pathogens - particularly corn   Mushrooms - some food value  

62 Basidiomycota – Club Fungi

63 Ascomycota – Sac Fungi Includes yeasts, molds, mildews, and morels - terrestrial and aquatic species.   Have septate or unicellular hyphae   Reproduction   Asexual   Spores called Conidium – on Conidiophores   Yeast asexual reproduction is by Budding   Sexual   Two mating strains form male or female gametangia   Female gametangium – Ascogonium   Male gametangium – Antheridium   Gametangia fuse - nuclei pair but don't fuse   Hyphae intertwine form an Ascocarp - reproductive body  of ascomycete; contains sacs -Asci (ascus) that produce ascospores.   Yeast important – able to breakdown carbohydrates   Bread/Baking Industry - use carbon dioxide from anaerobic respiration   Brewing Industry - fermentation of juices/liquids  

64 Ascomycota – Sac Fungi

65 Deuteromycota Imperfect Fungi
Taxonomic holding tank - fungi that where no sexual reproductive phase has been discovered.   Have characteristics similar to ascomycetes   Classified on basis of asexual reproduction.   Aspergillis and Penicillium - former deuteromycetes now classified as ascomycetes   Aspergillis - ferments soy beans makes soy sauce   Penicillium - produce antibiotic penicillin; gives flavor to Roquefort and Camembert cheeses   Septate hyphae   Terrestrial species   Asexually Reproduce by conidia.  

66 Deuteromycota Imperfect Fungi

67 Symbiotic Relationships
MUTUALISM - type of symbiosis in which both organisms benefit Examples Mycorrhizae Symbiotic association between fungi and plant roots Lichens Symbiotic association between a fungus (usually an ascomycete and a green algae or cyanobacteria

68 Mycorrhizae Symbiosis between fungi and plant roots
Help plants absorb water and nutrients Fungus forms extensive network of hyphae in soil - increases surface area.   Action of fungal enzymes provide nutrients that can be readily absorbed by the plant.   Fungi absorbs of sugar produced by plant

69 Mycorrhizae

70 Lichens Symbiosis between a fungus (usually an ascomycete and a green algae or cyanobacteria Considered symbiotic-may be a controlled parasitism Fungal hyphae penetrate algal cells and absorb food Fungal member provides some protection against drying of algae. Lichens classified according to thallus   Crustose - grow surface of rocks and trees   Foliose - have leafy thallus   Shrubby - upright growth; also called 2-fold lichens  

71 Lichens

72 Disease Any change, other than injury, that interferes in normal functioning of a body.   Pathogen - Disease causing microorganism Infection - Invasion of a body by a pathogen.

73 Germ Theory of Disease Idea that disease is caused by microorganisms.
Earlier belief was that disease was caused by evil spirits, magic, or miasmas (vapors of marshes or decaying organic matter.)   Based on work of Louis Pasteur (French) and Robert Koch (German)   Koch’s Postulates   Microorganism should always be found in host but not in a healthy organism.   Microorganism must be isolated and grown in pure culture away from host.   When microorganisms of pure culture are injected into new host, they should cause disease.   Microorganisms should be reisolated from second host and grown in pure culture and identified as the same as the original pure culture.  

74 Germ Theory of Disease

75 Disease Agents of Disease   Viruses   Bacteria   Fungi   Protozoa  

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