Microorganisms
description
Transcript of Microorganisms
MICROORGANISMS
VirusesBiological particle composed of genetic
material and proteinCause diseases
Virulent –immediateTemperate - not immediately
Obligate Parasite - only reproduces in a living host
VirusesComparison 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.
VirusesViral 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.
Viruses
VirusesClassification
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.
VirusesBacteriophage(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
Viruses
VirusesLytic Cycle - fundamental reproductive
process of viruses
Consists of 5 phases.AttachmentEntry Replication Assembly Release
Viruses
VirusesLysogenic 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
Viruses
VirusesEvolution
Believed to have evolved after cells
May be simplification of some existing cells.
Kingdoms Eubacteria and Archaebacteria
Most common members - bacteria Bacteria Characteristics
Prokaryotic - no nucleusMicroscopic Heterotrophs or autotrophs
Evolution Fossil monerans - 3.5 billion years old. Evolved into many forms - live in different environments. Classification difficult; rely on physiology
Kingdoms Eubacteria and Archaebacteria
Classification - 2 Kingdoms Kingdom Archaebacteria
Kingdom Eubacteria
Kingdom Archaebacteria Adapted to harsh environments
Include methanogens, extreme halophiles, and thermoacidophiles. Methanogens AnaerobicUse carbon dioxide and hydrogen to form methaneLive 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
Kingdom Archaebacteria
Kingdom EubacteriaAll members of which we commonly call Bacteria Identification
Classified on basis of shape Coccus - spherical shaped cellsBacillus - Rod shaped cells Spirillum - Shaped like coiled rods or corkscrews
Cells can cluster together or form chains or filaments Staphylo - clusterStrepto -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
Kingdom Eubacteria
Kingdom EubacteriaTwo specialized Phyla Phylum Cyanophyta
Blue-green bacteria (algae)Similar to plants and plant-like protistsPhotosynthetic - produce food and oxygen.Clump to form coloniesExhibit some division of labor
Phylum ProchlorophytaPhotosynthetic
Live symbiotically with tunicatesChlorophyll similar to eukaryotes.
Biology of BacteriaStructure 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
Biology of Bacteria
Biology of BacteriaNutrition
May be heterotrophic or autotrophic
Most are HeterotrophicSaprophyte feeds on dead or decaying matter. Parasite feeds on living materials
Some AutotrophicPhotoautotrophs - use sunlight as energy source. Chemoautotrophs - use energy of chemical reactions to synthesize food. Nitrogen Fixation - gaseous nitrogen converted into ammonia compounds
Biology of BacteriaRespiration
Obligate Anaerobes - cannot survive in presence of oxygen.
Facultative Anaerobes - can live with or without oxygen.
Obligate Aerobes - cannot live without oxygen.
Biology of BacteriaReproduction
Some reproduce rapidly - divide every 15-20 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
Biology of BacteriaToxin 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 bacteriaSymptoms - fever, weakness, and damage to circulatory system
Example - Typhoid Fever. Exotoxin - products of bacterial metabolism Secreted into area around bacteria Most potent poisons knownExamples - Diphtheria and Botulism (food poisoning)
Biology of Bacteria
Kingdom ProtistaCharacteristics 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.
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
ProtozoaGeneral 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 zooplanktonUnicellular, heterotrophic organisms that drift in water. Parasitic forms cause disease
Protozoa
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
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
Sarcodina - Amoeba
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 activitiesMicronucleus - 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 vacuolesContents 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 (-)
Ciliophora - Paramecium
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
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.
Sporozoa
AlgaeGeneral 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.
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
Chlorophyta – “Green” Algae
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.
Chrysophyta – “Golden Brown” Algae
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
Pyrrophyta – “Fire” Algae
Euglenophyta – “True Eye” Algae
Have characteristics of green algae and protozoa.Contain chlorophylls a and b, carotenes in some.Food stored as a starch - ParamylonHave no cell wall, surrounded by pellicleNot 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
Euglenophyta – “True Eye” Algae
Fungus Like ProtistsMembers of group traditionally classified as
fungi - actually are protists Life cycles look fungus like
Store food as glycogen Morphological differences considered
superficial
Fungus Like ProtistsPhylum 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
Fungus Like Protists
Fungus Like ProtistsPhylum 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
Fungus Like Protists
Kingdom FungiDiverse 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.
Kingdom FungiCharacteristics
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.
Kingdom FungiCharacteristics
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 nucleiHomokaryotic - similar nuclei.
Kingdom FungiClassification 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
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 1845-47 Result - mass migration of Irish to United States.
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
Zygomycota – Rhizopus Bread Mold
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 portionCap - flattened top portion
Gills - radiating rows under cap - site of basidia;
Basidium - club-shaped reproductive cell; produces Basidiospores
Hyphae grows - septa form - called Primary MyceliumHyphae 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
Basidiomycota – Club Fungi
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
Ascomycota – Sac Fungi
DeuteromycotaImperfect 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.
DeuteromycotaImperfect Fungi
Symbiotic RelationshipsMUTUALISM - type of symbiosis in which both
organisms benefit
Examples MycorrhizaeSymbiotic association between fungi and plant rootsLichensSymbiotic association between a fungus (usually an ascomycete and a green algae or cyanobacteria
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
Mycorrhizae
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
Lichens
DiseaseAny change, other than injury, that
interferes in normal functioning of a body.
Pathogen - Disease causing microorganism
Infection - Invasion of a body by a pathogen.
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.
Germ Theory of Disease
DiseaseAgents of Disease
Viruses Bacteria Fungi Protozoa