Exam 1 Notes - exam 1 PDF

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Exam 1 Notes Chapter 1  Microorganisms  organisms that are too small to be seen with the unaided eye o Include bacteria, fungi, protozoa, microscopic algae, & viruses o A few are pathogenic  disease-producing  Scientific nomenclature o Established by Carolus Linnaeus in 1735 o Organisms have two name; the genus and the specific epithet (species)  Types of microorganisms o Bacteria  Prokaryotes & single-celled  Peptidoglycan cell walls  Divide via binary fission  Derive nutrition from organic/inorganic chemicals or photosynthesis o Archaea  Prokaryotes  Lack peptidoglycan cell walls  Often live in extreme environments  Include: methanogens, extreme halophiles & thermophiles o Fungi  Eukaryotes; distinct nucleus  Chitin cell walls  Absorb organic chemicals for energy  Yeasts are unicellular; molds/mushrooms are multicellular  Molds consist of masses of mycelia, which are composed of filaments called hyphae o Protozoa  Eukaryotes  Absorb/ingest organic chemicals  May be motile via pseudopods, cilia, flagella  Free-living or parasitic (derive nutrients from a living host) o Algae  Eukaryotes  Cellulose cell walls  Found in freshwater, saltwater, and soil  Use photosynthesis for energy  Produce oxygen and carbohydrates o Viruses  Acellular  Consist of DNA/RNA core surrounded by a protein coat  Coat may then be enclosed in a lipid envelope

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Are replicated only when they are in a living host cell; inert outside living hosts o Multicellular animal parasites  Eukaryotes  Multicellular animals  Not strictly microorganisms  Parasitic flatworms/roundworms are called helminthes (some microscopic stages in their life cycles) Classification of microorganisms o 3 domains based on cellular organization; developed by Carl Woese  bacteria  archaea  eukarya  protists, fungi, plants, animals Robert Hooke  1665; reported that living things are composed of little boxes or “cells” o marked the beginning of cell theory  all living things are composed of cells Anton van Leeuwenhoek  observed the first microbes from 1623 – 1673; viewed “animalcules” through magnifying lenses Spontaneous generation vs biogenesis o Spontaneous Generation  the hypothesis that life arises from nonliving matter; a “vital force” is necessary for life o Biogenesis  the hypothesis that living cells arise only from preexisting living cells o Francesco Redi  1668; filled jars with decaying meat and checked for maggots o John Needham  1745; put boiled nutrient broth into cover flasks and checked for microbial growth o Lazzaro Spallanzani  1765; boiled nutrient solutions in sealed flasks and checked for microbial growth o Rudolf Virchow  1858; said cells arise from preexisting cells o Louis Pasteur  1861; demonstrated that microorganisms are present in the air  Used s-shaped flasks; kept microbes in but let air out  Broth in flasks showed no signs of life; neck of flask traps microbes  Microorganisms originate in air/fluids, not mystical forces “golden age of microbiology” (1857 – 1914) o Pasteur showed that microbes are responsible for fermentation  the microbial conversion of sugar to alcohol in the absence of air  Microbial growth is also responsible for spoilage of food/beverages  Bacteria that use air spoil wine by turning it to vinegar (acetic acid) o Pasteur demonstrated that these spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine  Pasteurization  the application of a high heat for a short time to kill harmful bacteria in beverages

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Germ theory of disease o Agostino Bassi  1835; showed that a silkworm disease was caused by a fungus o Pasteur  1865; showed that another silkworm disease was caused by a protozoan o Ignaz Semmelweis  1840s; advocated hand washing to prevent transmission of puerperal fever from one obstetrical patient to another o Joseph Lister  1860s; used a chemical antiseptic (phenol) to prevent surgical wound infections by applying pasteur’s work showing that microbes are in the air, can spoil food, and cause animal diseases o Robert Koch  1876; discovered that a bacterium causes anthrax and provided the experimental steps, Koch’s postulates, to demonstrate that a specific microbe causes a specific disease Vaccinations o Edward Jenner  1796; inoculated a person with cowpox virus, who was then immune from smallpox; vaccination derived from Latin word vacca – cow o This protection is called immunity Birth of chemotherapy o Chemotherapy  the treatment of disease with chemicals  Chemotherapeutic agents used to treat infectious disease can be synthetic drugs or antibiotics  Antibiotics  chemicals produced by bacteria/fungi that inhibit or kill other microbes o First synthetic drugs  Quinine from tree bark was long used to treat malaria  Paul Ehrlich  speculated about a “magic bullet” that could destroy a pathogen without harming the host  1910; developed a synthetic arsenic drug, salvarsan, to treat syphilis  1930; Sulfonamides were synthesized o antibiotics  Alexander Fleming  1928; discovered the first antibiotic (by accident)  Observed that penicillium fungus made an antibiotic, penicillin, that killed s. aureus  1940; penicillin was tested clinically and mass-produced bacteriology  the study of bacteria mycology  the study of fungi parasitology  the study of protozoa and parasitic worms immunology  the study of immunity o vaccines are interferons are used to prevent and cure viral diseases o Rebecca lancefield  1933; classified streptococci based on their cell wall components, was a major advance in immunology

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Virology  the study of viruses o Dmitri Iwanowski (1892) and Wendell Stanley (1935)  discovered the cause of mosaic disease of tobacco as a virus o Electron microscopes have made it possible to study the structure of viruses in detail Recombinant DNA technology o Microbial genetics  the study of how microbes inherit traits o Molecular biology  the study of now DNA directs protein synthesis o Genomics  the study of an organism’s genes; has provided new tools for classifying microorganisms o Recombinant DNA  DNA made from 2 different source  Paul Berg  1960s; inserted animal DNA into bacterial DNA, and the bacteria produced an animal protein o George Beadle/Edward Tatum  1941; showed that genes encode a cell’s enzymes o Oswald Avery/Colin MacLeod/Maclyn McCarty  1944; showed that DNA is the hereditary material o James Watson/Francis Crick  1953; proposed a model of DNA structure o Francois Jacob/Jacques Monod  1961; discovered the role of mRNA in protein synthesis Biotechnology  the use of microbes for practical applications, such as producing foods/chemicals Recombinant DNA Technology  enables bacteria/fungi to produce a variety of proteins, vaccines, and enzymes o Missing/defective genes in human cells can be replaced in gene therapy o Genetically modified bacteria are used to protect crops from insects and from freezing

Chapter 3  Light microscopy  any kind of microscope that uses visible light to observe specimens o Many types of light microscopy  Compound light microscopy  Darkfield microscopy  light objects visible against a dark background  Phase-contrast microscopy  allows examination of living organisms and internal cell structures  Differential interference contrast (DIC) microscopy  similar to phasecontrast; uses 2 light beams/prisms to split light beams, giving more contrast/color to the specimen  Fluorescence microscopy  cells stained with fluorescent dyes (fluorochromes), which absorb UV light and emit longer wavelengths (visible light)  Confocal microscopy  short wavelength (blue) light is used to excite a single plane of a specimen; each plane is illuminated and a 3D image is constructed with a computer  Compound light microscopy o In a compound microscope, the image from the objective lens is magnified again by the ocular lens  Total magnification = objective lens x ocular lens o Resolution  the ability of the lenses to distinguish two points  Shorter wavelengths of light provide greater resolution o Refractive index  a measure of the light-bending ability of a medium  light may refract after passing through a specimen to an extent that it does not pass through the objective lens  immersion oil is used to keep light from refracting o brightfield illumination  dark objects are visible against a bright background; light reflected off the specimen does not enter the objective lens  electron microscopy o uses electrons instead of light; the shorter wavelength of electrons gives greater resolution o used for images too small to be seen with light microscopes (i.e. viruses) o transmission electron microscopy  a beam of electrons passes through ultrathin sections of a specimen, then through an electromagnetic lens, then focused on a projector lens  specimens may be stained with heavy-metal salts (i.e. gold) for contrast o scanning electron microscopy  an electron gun produces a beam of electrons that scans the surface of an entire specimen; secondary electrons emitted from the specimen produce a 3D image

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preparing smears for staining o staining  coloring microorganisms with a dye that emphasizes certain structures o smear  a thin film of a material containing microorganisms spread over a slide o microorganisms are fixed (attached) to the slide, which kills the microorganisms o live and/or unstained specimens have little contrast with the surrounding medium; live specimens are used to study cell behavior o chromophore  stains consist of a positive and negative ion, one of which is colored  basic dye  chromophore is a cation  acidic dye  chromophore is an anion o negative staining  staining the background instead of the cell simple stain  use of a single basic dye o highlights the entire microorganism to visualize cell shapes and structures o a mordant may be used to hold the stain or coat the specimen to enlarge it differential stains  used to distinguish between bacteria o gram stain  classifies bacteria into gram-positive or gram-negative  gram-positive bacteria have thick peptidoglycan cell walls  gram-negative bacteria have thin peptidoglycan cell walls and a layer of lipopolysaccharides o acid-fast stain  binds only to bacteria that have a waxy material in their cell walls, which is not decolorized by acid-alcohol  used to identify  mycobacterium; nocardia special stains  used to distinguish parts of microorganisms o capsule stain  capsules  gelatinous covering that do not accept most dyes  suspension of India ink/nigrosin contrasts the background with the capsule, which appears as a halo around the cell o endospore stain  endospores  resistant, dormant structures inside some cells that cannot be stained by ordinary methods  primary stain: malachite green, usually with heat; decolorize cells: water; counterstain: safranin  spores appear green within red/pink cells o flagella staining  flagella  structures of locomotion  uses a mordant and carbolfuchsin

Chapter 10  taxonomy  the science of classifying organisms o shows degree of similarity among organisms  systematics, or phylogeny  the study of the evolutionary history of organisms  the study of phylogenetic relationships o Linnaeus  1735; kingdoms Plantae and Animalia  1880s; bacteria and fungi put in kingdom Plantae (Nageli); Kingdom Protista proposed for bacteria, protozoa, algae, and fungi (Haeckel) o 1937; prokaryote introduced to distinguish cells without a nucleus o murray  1968; Kingdom Prokaryotae o whittaker  1969; five-kingdom system  the three domains o developed by Woese (1978); based on sequences of nucleotides in rRNA o eukarya  animals, plants, fungi o bacteria o archaea  methanogens, extreme halophiles, hyperthermophiles o eukaryotes originated from infoldings of prokaryotic plasma membranes o endosymbiotic bacteria developed into organelles (mitochondria/chloroplasts)  classification of prokaryotes o prokaryotic species  a population of cells with similar characteristics  culture  bacteria grown in a laboratory media  clone  population of cells derived from a single parent cell  strain  genetically different cells within a clone  classification of eukaryotes o Protista  a catchall kingdom for a variety of organisms; autotrophic and heterotrophic  Grouped into clades based on rRNA o Fungi  chemoheterothrophic; unicellular or multicellular; cell walls of chitin; develop from spores or hyphal fragments o Plantae  multicellular; cellulose cell walls; undergo photosynthesis o Animalia  multicellular; no cell walls; chemoheterotrophic  Classification of viruses o Not a part of any domain; not composed of cells; requires a host cell o Viral species  population of viruses with similar characteristics that occupies a particular ecological niche

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Chapter 12 - Fungi o Mycology  the study of fungi o Chemoheterotrophs (decompose organic matter) o Aerobic or facultative anaerobic Vegetative structures o Molds and fleshy fungi  The fungal thallus (body) consists of hyphae filaments; a mass of hyphae is a mycelium  Septate hyphae  contains cross-walls  Coenocytic hyphae  does not contain septa  vegetative hyphae obtain nutrients while aerial hyphae are involved with reproduction o yeasts  nonfilamentous and unicellular  budding yeasts divide unevenly; fission yeasts divide evenly o dimorphic fungi  yeastlike at 37C; moldlike at 25C fungal diseases o mycosis  fungal infection o systemic mycoses  deep within the body o subcutaneous mycoses  beneath the skin o cutaneous mycoses  affect hair, skin, nails o superficial mycoses  localized (i.e. hair shafts) o opportunistic mycoses  fungi harmless in normal habitat but pathogenic in a compromised host Lichens o Mutualistic combination of a green alga (or cyanobacterium) and fungus  Crustose – encrusted on the substratum  Foliose – leaflike  Fruticose – fingerlike o Thallus (body) of lichens are made of:  Medulla  hyphae grown around algal cells  Rhizines (holdfasts)  hyphae projections below the body  Cortex  protective coating over the algal layer o Alga produces and secretes carbohydrates; fungus provides holdfast o Economic importance: dyes, antimicrobial (usnea), litmus, food for herbivores Algae o Not a taxonomic group

o Unicellular or filamentous photoautotrophs o Lack roots, stems, and leaves o Mostly aquatic  Water is necessary for growth and reproduction

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Characteristics of algae o Locations depend on nutrient availability, wavelengths of light, and surfaces to attach o Thallus – body of multicellular algae  Consists of holdfasts, stipes, and blades o All reproduce asexually o Multicellular algae can fragment or reproduce sexually via alternation of generations Selected phyla of algae o Brown algae (kelp)  Cellulose and alginic acid cell walls  Multicellular and macroscopic  Produce align – thickener used in foods o Red algae  Have branched thalli  Most are multicellular  Harvested for agar and carrageenan  Some produce a lethal toxin o Green algae  Cellulose cell walls  Unicellular or multicellular  Chlorophyll a and b  Store starch  Gave rise to terrestrial plants o Diatoms  Pectin and silica cell walls  Unicellular or filamentous  Store oil  Produce domoic acid – cause neurological disease o Dinoflagellates  Cellulose in plasma membrane  Unicellular  Neurotoxins (saxitoxins) cause paralytic shellfish poisoning o Oomycota (water molds)  Cellulose cell walls  Chemoheterotrophic  Produce zoospores

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 Decomposers and plant parasites Roles of algae in nature o Fix CO2 into organic molecules; produce 80% of Earth’s O2 o Algal blooms  increases in planktonic algae that can result in toxin release or die and consume oxygen o Oil production o Symbionts of animals Protozoa o Unicellular eukaryotes; Inhabit water and soil; Animal-like nutrition; Complex life cycles o Feeding and growing form is a trophozoite o Asexual reproduction is by fission, budding, or schizogony (multiple fission) o Sexual reproduction is by conjugation o Some produce a cyst to survive adverse conditions Characteristics of protozoa o Require a large supply of water o Many have an outer protective pellicle, requiring specialized structures to take in food  Ciliates wave cilia toward mouth-like cytosome  Amebae phagocytize food o Food is digested in vacuoles and wastes eliminated through an anal pore slime molds o cellular slime molds  ingest fungi/bacteria by phagocytosis; resemble ameba  cells aggregate to form stalks and spore caps that differentiate into spores o plasmodial slime molds  mass of protoplasm with multiple nuclei; moves as a giant ameba  cytoplasmic streaming  protoplasm moves and changes speed and direction to distribute oxygen and nutrients helminthes  parasitic worms o 2 phyla: Platyhelminthes (flatworms); nematoda (roundworms) characteristics of helminthes o multicellular eukaryotic animals o specialized to live in hosts  may lack digestive system  reduced nervous system  reduced or lacking locomotion  complex reproductive system platyhelminths o trematodes (flukes)  flat, leaf-shaped  ventral and oral sucker  absorb food through cuticle covering

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o cestodes (tapeworms)  scolex  head that has suckers for attachment  absorb food through cuticle  proglottids  body segments; contain male and female reproductive organs  humans as definitive hosts  eggs from proglottids are ingested, hatch into larvae, and bore into the intestinal wall  produce cysticerci  humans as intermediate hosts  eggs are ingested and hatch in the intestine  larvae migrate to the liver or lungs and develop a hydatid cyst nematodes (round worms) o cylindrical; complete digestive system o dioecious; males contain spicules o free-living and parasitic o larvae infective for humans  stronglyoides – reemerging infection  necator americanus/anclyostoma duodenale – hookworms; enter the skin and are carried to the intestines  dirofilaria immitis – spread by mosquitoes; causes heartworm arthropods as vectors o arthropods  animals with segmented bodies, hard external skeletons, and jointed legs o vectors  arthropods that carry pathogenic microorganisms o representative classes:  arachnida – 8 legs  crustacean – 4 antennae  insecta – 6 legs o mechanical transmission o biological transmission  pathogen multiplies in the vector o definitive host  microbe’s sexual reproduction takes place in the vector

Chapter 4  comparing prokaryotic and eukaryotic cells o prokaryote  comes from the Greek words for prenucleus  1 circular chromosome, not in a membrane  no histones or organelles  bacteria: peptidoglycan cell walls; archaea: pseudomurein cell walls  divides by binary fission o eukaryote  comes from the Greek words for true nucleus  paired chromosomes in nuclear membrane  contains histones and organelles  polysaccharide cell walls. When present  divides by mitosis  shapes of bacterial cells o bacillus (rod-shaped) o coccus (spherical) o spiral  vibrio; spirillum; spirochete o star-shaped o rectangular  arrangements of bacterial cells o pairs  diplococci, diplobacilli o clusters  staphylococci o chains  streptococci, streptobacilli o groups of 4  tetrads o cubelike groups of 8  sarcinae  glycocalyx o external to the cell wall; viscous and gelatinous o made of polysaccharide and/or polypeptide o 2 types: capsule – neatly organized and firmly attached; slime layer – unorganized and loose o contribute to virulence  capsules prevent phagocytosis  extracellular polymeric substance helps form biofilms  flagella o filamentous appendages external of the cell; propel bacteria; made of protein flagellin o 3 parts:

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filament – outermost region hook – attac...