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Microbiology Chapter 1

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Termini in questo insieme (89)

  • What are the three domains of life?

    Bacteria, Archaea, and Eukarya.

  • What type of cells are Bacteria?

    Prokaryotes; usually undifferentiated single cells

  • What type of cells are Archaea?

    Prokaryotes; mostly extremophiles, none disease-causing

  • What organisms belong to Eukarya?

    Plants, animals, fungi, and protists

  • What is the major difference between prokaryotic and eukaryotic cells?

    Eukaryotes have membrane-enclosed structures/organelles; prokaryotes do not have a nucleus (prokaryote = before nucleus, eukaryote = true nucleus)

  • What structures are found in cells regardless of whether they are prokaryotic or eukaryotic?

    Ribosomes, genomes (DNA), cell membranes, and cytoplasm

  • Why is rRNA useful for phylogenetic analysis?

    rRNA is found in all cells and contains highly conserved sequences

  • What did Carl Woese discover using rRNA sequence analysis?

    He discovered that rRNA from methanogens was distinct from Bacteria and Eukarya and named the new group Archaea

  • What does LUCA stand for?

    Last universal common ancestor

  • Why are viruses considered nonliving?

    Viruses lack the cellular properties/processes required for independent life

  • Why were cyanobacteria important in the evolution of life on Earth?

    Cyanobacteria oxygenated Earth's atmosphere

  • Why is staining important when viewing bacteria with bright-field microscopy?

    Bacteria lack contrast, making them difficult to see; staining increases contrast

  • What is magnification?

    The ability to enlarge an image

  • What is total magnification?

    Objective lens magnification x ocular lens magnification

  • What is resolution?

    The ability to distinguish two adjacent objects as distinct and separate

  • What is numerical aperature?

    The light-gathering ability of the objective lens

  • Why is immersion oil used with the 100x objective?

    To increase the light viewed by the lens

  • What do basic dyes do when staining bacteria?

    They are positively charged and bind strongly to negatively charged cell components such as nucleic acids, acidic polysaccharides, and cell surfaces

  • What is a simple stain?

    A stain that uses one stain/dye

  • What does a differential stain do?

    Renders different kinds of cells different colors

  • What is an example of a differential stain?

    The Gram stain, which differentiates cells based on differences in cell wall structure

  • What is characteristic of bright-field microscopy?

    Organisms are stained; however, stains can kill cells and distort features

  • What is phase-contrast microscopy used for?

    Improving image contrast of unstained, live cells; the resulting image shows dark cells on a light background

  • What is characteristic of dark-field microscopy?

    Live, unstained cells appear light against a dark background; it is good for observing motility such as flagella

  • What is characteristic of differential interference contrast (DIC) microscopy?

    It uses a polarizer to create two beams of polarized light and gives structures such as nuclei and bacterial inclusions a three-dimensional appearance

  • What is fluorescence microscopy used for?

    To visualize specimens that fluoresce naturally or after staining with a fluorescent dye

  • What does DAPI stain?

    DNA

  • What does confocal scanning laser microscopy (CSLM) produce?

    A three-dimensional image by focusing a laser on individual specimen layers and compiling those layers

  • What do electron microscopes use to image cells?

    Electrons instead of visible light; electromagnets function as lenses

  • What are the two types of electron microscopes?

    Transmission electron microscope (TEM) and scanning electron microscope (SEM)

  • What does TEM primarily allow you to visualize?

    Internal cell structures at very high magnifications

  • What does SEM primarily allow you to visualize?

    The surface of a specimen

  • What is the difference between SEM and TEM?

    SEM: visualizes the specimen surface; specimen is coated with heavy metal

    TEM: uses a very thin specimen and allows internal cell structures to be viewed at very high magnification

  • What was Robert Hooke's contribution to microbiology?

    He was the first to discover microbes, published Micrographia in 1665, and illustrated reproductive structures of molds

  • What was Antonie van Leeuwenhoek's contribution to microbiology?

    He used a light microscope and was the first to see bacteria, which he called "wee animalicules"

  • What is spontaneous generation?

    The idea that life comes from nonliving items

  • What is biogenesis?

    The idea that life emerges from existing life

  • What did Pasteur's swan-necked flask experiment demonstrate?

    It disproved spontaneous generation and supported the idea that air contained contaminating microbes

  • What did Pasteur discover about alcoholic fermentation?

    Alcoholic fermentation is a biological process rather than merely a chemical process

  • What were Pasteur's contributions to microbiology?

    His work led to sterilization methods and food preservation, and he developed vaccines for anthrax, fowl cholera, and rabies

  • What was Joseph Lister's contribution to microbiology?

    He developed surgical antiseptic techniques, including disinfecting surgical tools with carbolic acid

  • What was Ignaz Semmelweis's contribution to microbiology?

    He promoted handwashing to prevent infections, although he did not know why it worked

  • What is aseptic technique?

    Practices that allow preparation and maintenance of sterile media and solutions by preventing the introduction and growth of microbes

  • What is the difference between aseptic technique and sterilization?

    Aseptic techniques prevent microbial growth and use sterile tools/spaces; sterilization eliminates microbes

  • What major positive applications of microbes are emphasized in Chapter 1?

    Vaccination and antibiotic therapy, water and wastewater treatment, and food production

  • What major negative impact of microorganisms is emphasized?

    Microorganisms can act as disease agents, including bacterial and viral pathogens

  • Are most microorganisms harmful?

    No; most microorganisms are beneficial

  • What shape are cocci?

    Spherical or ovoid

  • What shape are bacilli?

    Cylindrical rods

  • What shape is spirillum?

    Rigid spiral

  • What shape is spirochete?

    Flexible spiral

  • What shape is vibrio?

    Slightly curved or comma-shaped

  • What are other bacterial morphologies listed?

    (Not cocci, bacilli, spirillum, spirochete, or vibrio)

    Appendaged (stalks/hyphae), irregular/asymmetrical (budding), and filamentous bacteria

  • What does diplo- indicate?

    Cells arranged in pairs

  • What does strepto- indicate?

    Cells arranged in chains

  • What does staphylo- indicate?

    Cells arranged in grapelike clusters

  • What arrangement of cells is described as three-dimensional cubes?

    Tetrad or sarcina

  • Why do bacteria form different cell arrangements?

    Cells can remain attached during cell division

  • What is growth media (culture media)?

    Mixtures of nutrients that support growth in an artificial setting

  • What are the four types of growth media?

    Plates, deeps, slants, and broths

  • Which types of growth media are solid?

    Plates, deeps, and slants

  • Which type of growth media is a liquid?

    Broth

  • What is the purpose of agar in growth media?

    It is a solidifying agent that allows for isolation

  • What did Robert Koch demonstrate about infectious diseases?

    He experimentally demonstrated the link between microbes and infectious diseases

  • What diseases did Koch identify the causative agents of?

    Anthrax, tuberculosis, and cholera

  • What is Koch's 1st postulate?

    The same organism must be present in every case of the disease

  • What is Koch's 2nd postulate?

    The organism must be isolated from the diseased host and grown as a pure culture

  • What is Koch's 3rd postulate?

    The isolated organism should cause the same disease when inoculated into a susceptible host

  • What is a susceptible host?

    A host that can develop the disease

  • What is Koch's 4th postulate?

    The organism must be re-isolated from the inoculated, diseased animal

  • What major microbial process is Winogradsky associated with?

    Chemolithotrophy

  • What is chemolithotrophy?

    Oxidation of inorganic compounds to yield energy

  • What did Winogradsky demonstrate about bacteria and biogeochemical transformations?

    Specific bacteria are linked to specific transformations, such as the nitrogen and sulfur cycles

  • What sulfur oxidizer did Winogradsky study?

    Beggiatoa

  • What did Winogradsky demonstrate about the carbon source of chemolithotrophs?

    They use carbon from CO2 (autotrophy)

  • What culture technique did Beijerinck develop?

    Enrichment culture techniques

  • What do enrichment culture techniques do?

    Selectively encourage the growth of specific organisms

  • What aerobic nitrogen-fixing bacterium did Beijerinck isolate?

    Azotobacter

  • What processes was Beijerinck first to demonstrate?

    Nitrogen fixation and nitrification

  • What organism is associated with Beijerinck's demonstration of nitrogen fixation?

    Clostridium pasteurianum

  • What virus did Beijerinck first observe?

    Tobacco mosaic virus

  • What bacterium did Frederick Griffith use in his experiment?

    Streptococcus pneumoniae

  • Which strain was virulent in Griffith's experiment?

    The S strain

  • Which strain was nonvirulent in Griffith's experiment?

    The R strain

  • What did Griffith's experiment demonstrate?

    Bacteria can transfer genetic information

  • What is the transfer of genetic information demonstrated by Griffith called?

    Transformation

  • Which experiment later investigated the transforming principle described by Griffith?

    The Avery-MacLeod-McCarty experiment (1944)

  • How did Avery-MacLeod-McCarty build on Griffith's experiments?

    They repeated Griffith's experiments using just DNA

  • What did the Avery-MacLeod-McCarty experiment show?

    DNA is the genetic material of cells