MICROORGANISMS

Viruses

Biological particle composed of genetic material and protein

Cause diseasesVirulent –immediateTemperate - not immediately

Obligate Parasite - only reproduces in a living host

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.

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.  

Viruses

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.  

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

Viruses

Viruses

Lytic Cycle - fundamental reproductive process of viruses

Consists of 5 phases.AttachmentEntry  Replication  Assembly  Release  

Viruses

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  

Viruses

Viruses

Evolution

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 Eubacteria

All 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 Eubacteria

Two 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 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  

Biology of Bacteria

Biology of Bacteria

Nutrition  

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 Bacteria

Respiration  

Obligate Anaerobes - cannot survive in presence of oxygen.  

Facultative Anaerobes - can live with or without oxygen.  

Obligate Aerobes - cannot live without oxygen.  

 

Biology of Bacteria

Reproduction  

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 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 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 Protista

Characteristics   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  

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 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

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.  

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 Protists

Members of group traditionally classified as fungi - actually are protists

  Life cycles look fungus like  

Store food as glycogen   Morphological differences considered

superficial  

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  

Fungus Like Protists

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  

Fungus Like Protists

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.  

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.   

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 nucleiHomokaryotic - similar nuclei.

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  

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 Relationships

MUTUALISM - type of symbiosis in which both organisms benefit

Examples Mycorrhizae

Symbiotic association between fungi and plant rootsLichens

Symbiotic 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

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.

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

Disease

Agents of Disease  

Viruses   Bacteria   Fungi   Protozoa