Bacterial Cell Walls and Staining Quiz
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Questions and Answers

What is the primary function of sex pili in bacterial cells?

  • They enable movement towards nutrients.
  • They assist in the exchange of genetic material. (correct)
  • They help in the replication of DNA.
  • They protect the bacterium from environmental stress.

    • What is the role of bacteriophages in bacterial reproduction?

  • They help bacteria absorb nutrients.
  • They serve as a vector for gene transfer. (correct)
  • They provide energy for bacteria.
  • They reproduce independently of bacteria.

    • Which group of Archaea is strictly anaerobic and generates methane?

  • Extreme thermophiles
  • Thermophilic Acidophiles
  • Methanogens (correct)
  • Extreme halophiles

    • What is a characteristic of extreme halophiles?

    <p>They require high salt concentrations for growth.</p> Signup and view all the answers

    Where would you most likely find extreme thermophiles?

    <p>Near volcanic vents.</p> Signup and view all the answers

    Which statement accurately describes the cell walls of archaeans?

    <p>They include pseudo peptidoglycan.</p> Signup and view all the answers

    What distinguishes thermophilic extreme acidophiles from other archaea?

    <p>They thrive in extremely acidic environments.</p> Signup and view all the answers

    Which group of Archaea generally represents obligate aerobes?

    <p>Extreme halophiles</p> Signup and view all the answers

    Which group of microorganisms thrives at temperatures around 60ºC?

    <p>Thermophiles</p> Signup and view all the answers

    What type of microbe requires oxygen at reduced levels for growth?

    <p>Microaerophiles</p> Signup and view all the answers

    Which of the following is NOT a characteristic of true fungi?

    <p>Reproduce only asexually</p> Signup and view all the answers

    Which term refers to the study of fungal toxins and their effects?

    <p>Mycotoxicology</p> Signup and view all the answers

    Which type of fungi typically grows below a pH of 6?

    <p>Acidophiles</p> Signup and view all the answers

    What are wall teichoic acids primarily attached to in Gram-positive bacteria?

    <p>Peptidoglycan</p> Signup and view all the answers

    What type of fungal hyphae contains multiple nuclei without cell wall separation?

    <p>Coenocytic hyphae</p> Signup and view all the answers

    What step in the Gram staining process comes after applying the primary stain?

    <p>Add a mordant</p> Signup and view all the answers

    Which category includes microbes that can tolerate high salt concentrations up to 15-30%?

    <p>Halophiles</p> Signup and view all the answers

    What is the term for diseases caused by fungi in animals?

    <p>Mycoses</p> Signup and view all the answers

    Which of the following categories do organisms that utilize sunlight for energy belong to?

    <p>Photoautotrophs</p> Signup and view all the answers

    What type of nutritional class would a bacterium that uses glucose as an organic molecule for carbon source belong to?

    <p>Heterotrophs</p> Signup and view all the answers

    Which nutritional type uses reduced inorganic compounds as an electron source?

    <p>Lithotrophs</p> Signup and view all the answers

    What distinguishes differential staining from other staining methods?

    <p>It distinguishes organisms based on their staining properties</p> Signup and view all the answers

    Which of the following is NOT a step in the Gram staining process?

    <p>Applying a reducing agent</p> Signup and view all the answers

    What type of bacteria are represented by purple non-sulfur bacteria?

    <p>Photoorganoheterotrophs</p> Signup and view all the answers

    What is the primary outcome for the host cell in the lytic cycle?

    <p>The host cell undergoes lysis and dies.</p> Signup and view all the answers

    Which process allows phages to attach to host cells?

    <p>Binding of plate and tail fibers</p> Signup and view all the answers

    In the lysogenic cycle, what is the term used for the integrated viral nucleic acid within the bacterial chromosome?

    <p>Prophage</p> Signup and view all the answers

    What characterizes the replication timing of the lytic cycle compared to the lysogenic cycle?

    <p>Lysogenic cycle involves a dormant phase before replication.</p> Signup and view all the answers

    What component helps in the breakdown of the host cell wall during the lytic cycle?

    <p>Lysozyme</p> Signup and view all the answers

    Which organism is primarily responsible for causing thrush?

    <p>Candida albicans</p> Signup and view all the answers

    What is the main method of transmission for candidiasis?

    <p>Sexually</p> Signup and view all the answers

    Which of the following best describes a common symptom of dermatophytosis?

    <p>Blister-like lesions</p> Signup and view all the answers

    What is the typical preventive measure for preventing aspergillosis?

    <p>Staying away from sources of mold</p> Signup and view all the answers

    Which of the following best defines protozoa?

    <p>Unicellular, lack cell walls, and can be free living or parasitic</p> Signup and view all the answers

    What mechanism of reproduction is NOT associated with protozoa?

    <p>Fertilization</p> Signup and view all the answers

    Which type of nutritional strategy do protozoa NOT utilize?

    <p>Chemolithotrophic</p> Signup and view all the answers

    What symptom is indicative of candidiasis?

    <p>Itching and burning pains</p> Signup and view all the answers

    Study Notes

    Bacterial Cell Wall

    • Wall teichoic acid (WTA) is attached to peptidoglycan and lipoteichoic acid (LTA) to the cytoplasmic membrane via a lipid anchor.
    • Gram-positive bacteria have both WTA and LTA.

    Gram Staining Process

    • Heat fix/attach bacteria to a slide.
    • Add crystal violet as the primary stain.
    • Add Gram’s iodine as the mordant.
    • Decolorize with ethanol, acetone or a mixture of both.
    • Counter-stain with safranin.

    Peptidoglycan

    • It is a rigid layer found in bacterial cell walls.
    • It's a thin sheet composed of N-acetylglucosamine, N-acetylmuramic acid, and several amino acids.

    Endotoxin

    • It's the lipopolysaccharide portion of the cell envelope in some Gram-negative bacteria.
    • It's toxic to humans when released.

    Nutritional Types of Bacteria

    • Autotrophs use inorganic carbon dioxide as their carbon source.
    • Heterotrophs use organic molecules like glucose as their carbon source.
    • Photoautotrophs use sunlight as their energy source.
    • Chemoautotrophs use inorganic chemicals as their energy source.
    • Lithotrophs use reduced inorganic compounds as their electron source.
    • Organotrophs use reduced organic compounds as their electron source.

    Photolithoautotrophs

    • Use inorganic CO2 as a carbon source.
    • Use sunlight as an energy source.
    • Use inorganic electron donors like water or hydrogen sulfide.
    • Examples include purple, green sulfur bacteria, and Cyanobacteria.

    Photoorganoheterotrophs

    • Use organic molecules like glucose as a carbon source.
    • Use sunlight as an energy source.
    • Use organic matter as an electron source.
    • Examples include purple non-sulfur bacteria and green non-sulfur bacteria.
    • Some can also grow as photolithoautotrophs with molecular hydrogen as an electron donor.

    Bacterial Sexual Reproduction

    • Conjugation is a process where the donor cell (with a fertility factor) transfers its DNA to the recipient cell by direct contact using sex pili.
    • Transduction uses bacteriophages to move foreign genes into a bacterial cell.
    • Transformation involves uptake of DNA from the environment by a bacterium.

    Archaea

    • Single celled prokaryotes.
    • Lack membrane-bound organelles and a nucleus.
    • Do not have true peptidoglycan but have pseudo-peptidoglycan in their cell walls.
    • Branched hydrocarbon chains in cell membrane lipids.
    • Many thrive in extreme environments.

    Archaea Classifications

    • Methanogens generate methane and are strictly anaerobic.
    • Extreme halophiles thrive in high saline environments and are typically obligate aerobes.
    • Extreme thermophiles/hyperthermophiles survive in hot environments (above 80°C) and can be aerobic, facultative aerobic, or anaerobic.
    • Thermophilic Extreme Acidophiles grow in extremely acidic hot environments.

    Physical factors Affecting Microbial Growth

    • Temperature: Psychrophiles (cold-loving), psychrotrophs (moderate cold), mesophiles (moderate warm), thermophiles (heat-loving), hyperthermophiles (very heat-loving).
    • Oxygen: Aerobes use oxygen; obligate aerobes require oxygen, microaerophiles need low oxygen levels, facultative aerobes can grow with or without oxygen. Anaerobes don't use oxygen; aerotolerant anaerobes can tolerate oxygen, and obligate anaerobes are sensitive to it.
    • pH: Acidophiles grow below pH 6.
    • Osmotic condition: Halophiles tolerate high salt concentrations; halotolerant organisms can tolerate low salt levels; non-halophiles are not tolerant to salt.

    Fungi

    • Eukaryotic, spore-bearing organisms.
    • Have absorptive nutrition.
    • Lack chlorophyll.
    • Reproduce sexually and asexually.

    General Characteristics of True Fungi

    • Eukaryotic, have nuclei and cytoplasmic organelles.
    • Most are filamentous (composed of hyphae), forming a network called a mycelium.
    • Some have septate hyphae, while others have non-septate (coenocytic hyphae) with many nuclei.
    • Some are unicellular, like yeasts.
    • Have rigid cell walls.

    Protozoa

    • Unicellular, lack cell walls.
    • Can be free-living or parasitic.
    • Mostly microscopic but some can be seen with the naked eye.
    • Move using pseudopodia, flagella, cilia, or direct cell movement; some are sessile.
    • Various nutritional types: autotrophs, heterotrophs, saprozoic.
    • Live in aquatic or terrestrial habitats as free-living or symbiotic organisms.
    • Reproduce asexually (fission, budding, cyst) or sexually (conjugation or syngamy).

    Bacteriophages

    • Viruses that infect bacteria.
    • Have a simple structure: head (containing DNA or RNA), tail sheath, plate, and tail fibers.
    • Attach to specific receptor sites on the bacterial cell wall.

    Phage Life Cycles

    • **Lytic cycle (virulent) ** destroys the host bacterium to release new phages (replication is independent of host cell).
    • Lysogenic cycle (temperate) integrates viral DNA into the host's genome, becoming a prophage and replicating synchronously with the host DNA. The host cell survives.

    Key Differences between Lytic and Lysogenic Cycles

    • Lytic cycle: Results in host cell death, virus replicates immediately; stages include attachment, entry/adsorption/penetration, replication, assembly, and lysis.
    • Lysogenic cycle: Allows host cell survival, dormant viral phase before replication; stages include attachment, entry/adsorption/penetration, integration, replication, assembly, and eventually lysis.

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    Description

    Test your knowledge on bacterial cell walls, including the structures like wall teichoic acid and peptidoglycan. This quiz also covers the Gram staining process and the nutritional types of bacteria. Ideal for microbiology students looking to reinforce their understanding of these critical concepts.

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