Presentation on theme: "Biological particle composed of genetic material and protein Cause diseases Virulent –immediate Temperate - not immediately Obligate Parasite - only reproduces."— Presentation transcript:
Biological particle composed of genetic material and protein Cause diseases Virulent –immediate Temperate - not immediately Obligate Parasite - only reproduces in a living host
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.
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.
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.
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
Lytic Cycle - fundamental reproductive process of viruses Consists of 5 phases. Attachment Entry Replication Assembly Release
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
Evolution Believed to have evolved after cells May be simplification of some existing cells.
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
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
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
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.
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
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
Respiration Obligate Anaerobes - cannot survive in presence of oxygen. Facultative Anaerobes - can live with or without oxygen. Obligate Aerobes - cannot live without oxygen.
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
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)
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.
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
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
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
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
Move by Cilia - short, hairlike projections Paramecium has rigid protein covering called Pellicl e - 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 (-)
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
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.
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.
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
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.
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
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
Members of group traditionally classified as fungi - actually are protists Life cycles look fungus like Store food as glycogen Morphological differences considered superficial
Phylum Acrasiomycota - Slime Molds Live mostly on land or in freshwater. Feeding stage - Myxameb a - 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
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
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.
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.
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.
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
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.
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
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
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
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.
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
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
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
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.
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.