Microorganisms

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 - 3.5 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 Saprophytefeeds on dead or decaying matter.   Parasitefeeds 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 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

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.   • 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, hairlikeprojections • 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 multicellulargametangia.   • 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