Bacterial Morphology and Structure Quiz
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Questions and Answers

Which term describes spherical shaped bacteria?

  • Cocci (correct)
  • Spirilla
  • Bacilli
  • Vibrios
  • What is the characteristic shape of spirochetes?

  • Rigid spirals
  • Straight rods
  • Curved or comma-shaped rods
  • Flexuous spirals (correct)
  • Which arrangement occurs when cocci divide in pairs?

  • Sarcan Packet
  • Streptococci
  • Tetrads
  • Diplococci (correct)
  • What distinguishes coccobacilli from regular bacilli?

    <p>Their length being equal to width (C)</p> Signup and view all the answers

    Which arrangement describes bacilli that form chains?

    <p>Streptobacilli (B)</p> Signup and view all the answers

    What type of bacteria are mycoplasma characterized as?

    <p>Lacking a stable morphology due to cell wall deficiency (D)</p> Signup and view all the answers

    Which of the following describes the primary structures of bacterial cell components?

    <p>Cell wall and cytoplasmic membrane (B)</p> Signup and view all the answers

    What is the name for square groups of four cocci cells?

    <p>Tetrads (B)</p> Signup and view all the answers

    What is the primary function of the bacterial cell wall?

    <p>To impart shape and rigidity to the cell (A)</p> Signup and view all the answers

    Which component primarily constitutes the dry weight of a gram-positive bacterial cell wall?

    <p>Peptidoglycan (B)</p> Signup and view all the answers

    What is the thickness of the gram-negative bacterial cell wall's peptidoglycan layer?

    <p>Single-unit thick (A)</p> Signup and view all the answers

    Which structure is unique to the outer membrane of gram-negative bacteria?

    <p>Lipopolysaccharide (LPS) (D)</p> Signup and view all the answers

    What is one major function of the outer membrane in gram-negative bacteria?

    <p>Acting as a selective barrier (B)</p> Signup and view all the answers

    How does the gram-positive bacterial cell wall differ chemically from that of gram-negative bacteria?

    <p>It has a thicker peptidoglycan layer (A)</p> Signup and view all the answers

    In gram-negative bacteria, what is the function of lipoproteins in the cell wall?

    <p>To anchor the outer membrane to the peptidoglycan (B)</p> Signup and view all the answers

    What is the average thickness of a gram-positive bacterial cell wall?

    <p>80 nm (D)</p> Signup and view all the answers

    What type of acids are found in the cell wall of gram-positive bacteria?

    <p>Teichoic acids (B)</p> Signup and view all the answers

    What can occur if the cell wall of a bacterium is weakened or ruptured?

    <p>The protoplast may swell and burst (A)</p> Signup and view all the answers

    What role do porins play in the outer membrane of gram-negative bacteria?

    <p>Transport nutrients into the cell (A)</p> Signup and view all the answers

    What term describes the process of bacterial cell destruction due to cell wall failure?

    <p>Lysis (C)</p> Signup and view all the answers

    What component primarily makes up the cytoplasmic (plasma) membrane of bacteria?

    <p>Lipid bilayer (C)</p> Signup and view all the answers

    Which amino sugars are part of the peptidoglycan structure in bacterial cell walls?

    <p>N-acetyl glucosamine and N-acetyl muramic acid (B)</p> Signup and view all the answers

    What is the primary component of the fungal cell wall that provides structural support?

    <p>Chitin (A)</p> Signup and view all the answers

    Which of the following types of spores are produced by mitosis?

    <p>Blastospore (C)</p> Signup and view all the answers

    What type of hyphae are characterized by the absence of cross walls?

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

    Which structure serves as the tangled mass of hyphae in molds?

    <p>Mycelium (C)</p> Signup and view all the answers

    What is the term for the change from yeast form to mycelial form in certain fungi in response to environmental factors?

    <p>Dimorphism (A)</p> Signup and view all the answers

    Which of the following components enhances the strength of the fungal cell wall?

    <p>Beta-glucans (C)</p> Signup and view all the answers

    Which type of fungal spore is formed by the fusion of cells followed by meiosis?

    <p>Basidiospore (C)</p> Signup and view all the answers

    What are the primary functions of the fungal cell wall?

    <p>Nutrient regulation and environmental protection (A)</p> Signup and view all the answers

    Dimorphic fungi can switch forms in response to environmental conditions. What typically triggers this switch?

    <p>Alterations in nutrients (C)</p> Signup and view all the answers

    What type of hyphae feature cross walls known as septa?

    <p>Septate hyphae (A)</p> Signup and view all the answers

    What is a primary function of the cytoplasmic membrane in bacteria?

    <p>Control of metabolite transport (C)</p> Signup and view all the answers

    Which layer is described as being easily washed off and lacks a defined association with the cell?

    <p>Slime layer (A)</p> Signup and view all the answers

    What type of proteins primarily compose bacterial flagella?

    <p>Flagellins (C)</p> Signup and view all the answers

    What is the role of sex pili in bacteria?

    <p>Transfer of DNA between cells (A)</p> Signup and view all the answers

    Which part of the flagellum serves as the connection between the filament and the basal body?

    <p>Hook (A)</p> Signup and view all the answers

    What composition is common for capsules and slime layers in bacteria?

    <p>Polysaccharides (D)</p> Signup and view all the answers

    What characteristic of capsules serves as a virulence factor in bacteria?

    <p>Protection from phagocytosis (D)</p> Signup and view all the answers

    What type of cellular structure is primarily found in the cytoplasm of bacteria?

    <p>Ribosomes (B)</p> Signup and view all the answers

    What process do ordinary pili primarily assist with in bacteria?

    <p>Adhesion to surfaces (A)</p> Signup and view all the answers

    Which rings are present in the basal body of flagella in gram-negative bacteria?

    <p>Four rings (D)</p> Signup and view all the answers

    What role does the capsule play in the identification of bacteria?

    <p>Provides specific capsular antigens (A)</p> Signup and view all the answers

    Which of the following is a function of the cytoplasmic membrane?

    <p>Generation of ATP (A)</p> Signup and view all the answers

    What is a major difference between fimbriae and flagella?

    <p>Flagella are used for motility, while fimbriae are not (B)</p> Signup and view all the answers

    What is the primary function of ribosomes in bacteria?

    <p>Protein synthesis (D)</p> Signup and view all the answers

    Which characteristic distinguishes eukaryotic ribosomes from bacterial ribosomes?

    <p>Size and sedimentation rate (A)</p> Signup and view all the answers

    What are mesosomes believed to be involved in during bacterial cell division?

    <p>DNA compartmentalization (D)</p> Signup and view all the answers

    What is the function of volutin granules in bacteria?

    <p>Storage of phosphate (A)</p> Signup and view all the answers

    Which structure in bacterial cells is analogous to mitochondria in eukaryotic cells?

    <p>Mesosome (A)</p> Signup and view all the answers

    What is a defining feature of the bacterial chromosome?

    <p>It is haploid and circular. (D)</p> Signup and view all the answers

    How do yeasts primarily reproduce?

    <p>Budding (A)</p> Signup and view all the answers

    Which of the following describes dimorphic fungi?

    <p>They can form both yeast and mycelial forms depending on temperature. (D)</p> Signup and view all the answers

    What term describes the tangled mass of hyphae in molds?

    <p>Mycelium (C)</p> Signup and view all the answers

    Which type of fungi primarily consists of single, unicellular organisms?

    <p>Yeasts (C)</p> Signup and view all the answers

    The study of fungi is referred to as what?

    <p>Mycology (B)</p> Signup and view all the answers

    What structure in fungi is responsible for nutrient absorption?

    <p>Vegetative mycelium (D)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of fungi?

    <p>Exist solely as multicellular organisms (C)</p> Signup and view all the answers

    What are the filamentous shapes in molds called?

    <p>Hyphae (C)</p> Signup and view all the answers

    Flashcards

    Cocci

    Spherical bacteria that can be found in pairs, chains, clusters, tetrads, or cubical packets.

    Bacilli

    Rod-shaped bacteria that can be arranged in chains or singly.

    Vibrios

    Curved or comma-shaped bacteria that are known for their characteristic vibratory motility.

    Spirilla

    Rigid spiral or helical bacteria often associated with movement.

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    Spirochetes

    Flexible spiral bacteria that have a corkscrew-like movement.

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    Mycoplasma

    Bacteria that lack a rigid cell wall and can take on various shapes, often appearing as round or oval bodies.

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    Binary Fission

    The process by which bacteria divide into two identical daughter cells, resulting in different arrangements.

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    Cell Envelope

    The outer layer of a bacteria, consisting of the cell wall and the plasma membrane.

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    Fungal Thallus

    The vegetative body of a fungus, ranging from single-celled yeasts to multicellular molds and mushrooms.

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    Chitin

    A strong, flexible polysaccharide found in the cell walls of fungi, composed of N-acetylglucosamine residues.

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    Yeast

    Single-celled fungi that reproduce asexually by budding or sexually through spore formation.

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    Hyphae

    Long, branched, thread-like filaments of cells that make up the fungal body.

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    Mycelium

    A tangled mass of hyphae, forming the main body of a fungus.

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    Coenocytic Hyphae

    Hyphae without cross walls, allowing protoplasm to flow freely.

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    Septate Hyphae

    Hyphae with cross walls (septa), with holes for cytoplasmic flow.

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    Sexual Spores

    Fungal spores formed through the fusion of cells and meiosis.

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    Asexual Spores

    Fungal spores produced by mitosis, without the fusion of cells.

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    Dimorphic Fungi

    Fungi that can exist in two forms, depending on environmental conditions, such as yeast and mold.

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    Bacterial Cell Wall

    The rigid outer layer of bacterial cells that provides shape, protection, and helps resist osmotic pressure.

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    Peptidoglycan

    A complex sugar molecule that forms the backbone of the bacterial cell wall, making it strong and rigid.

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    Lysis

    The process by which a bacterial cell bursts due to a weakened or ruptured cell wall, often caused by osmotic pressure changes.

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    Gram-Positive Bacterial Cell Wall

    A type of bacterial cell wall that is thicker and stronger, containing multiple layers of peptidoglycan and teichoic acids.

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    Gram-Negative Bacterial Cell Wall

    A type of bacterial cell wall that is thinner and less dense, containing a single layer of peptidoglycan and an outer membrane.

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    Teichoic Acids

    A group of negatively charged polymers found in the cell walls of gram-positive bacteria, contributing to their structural integrity.

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    Wall Teichoic Acid

    A type of teichoic acid found in gram-positive bacteria, linked to the peptidoglycan layer.

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    Membrane Teichoic Acid

    A type of teichoic acid found in gram-positive bacteria, linked to the cell membrane.

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    Lipopolysaccharide (LPS)

    A complex molecule that forms the outer layer of the gram-negative bacterial cell wall, acting as a protective barrier and contributing to pathogenicity.

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    Cytoplasmic (Plasma) Membrane

    A thin, flexible, and selectively permeable membrane that encloses the cytoplasm of a bacterial cell, controlling the passage of molecules in and out.

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    Cytoplasm

    The fluid inside the bacterial cell, containing the genetic material, ribosomes, and other essential components.

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    Porins

    Proteins that span the bacterial outer membrane, forming channels that allow passage of specific molecules like nutrients.

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    Periplasmic Space

    The space between the outer membrane and the plasma membrane in gram-negative bacteria, containing enzymes and transport proteins.

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    Periplasm

    A gel-like substance found in the periplasmic space of gram-negative bacteria, containing degrading enzymes involved in nutrient breakdown and transport.

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    Lipid A

    The structural component of LPS that anchors it to the outer membrane of gram-negative bacteria.

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    Bacterial Ribosomes

    The site for all protein synthesis in bacteria; these are slightly smaller than eukaryotic ribosomes and have a sedimentation rate of 70S.

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    Mesosomes

    Invaginations of the plasma membrane into the cytoplasm of bacteria; can be involved in DNA compartmentalization and respiration.

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    Intracytoplasmic Inclusions

    Storage bodies in bacteria that can vary depending on the nutrient availability and growth conditions.

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    Bacterial Chromosome

    A long, circular molecule of DNA found in bacteria; it is not associated with histones and replicates by simple fission.

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    Fungi

    Eukaryotic organisms that reproduce sexually and asexually, lack chlorophyll, and have absorptive nutrition.

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    Aerial Hyphae

    Hyphae that extend above the mycelium and bear the reproductive structures.

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    Vegetative Hyphae

    Hyphae that penetrate the supporting medium and absorb nutrients from it.

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    Mycology

    The study of fungi.

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    What is the function of the cytoplasmic membrane?

    A semipermeable barrier that controls the movement of molecules in and out of the bacterial cell.

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    Yeast-like fungi

    Yeast-like fungi that grow partly as yeast and partly as elongated cells resembling hyphae.

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    Zygomycetes

    A group of medically important molds, characterized by rarely septated hyphae.

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    What is another key function of the cytoplasmic membrane?

    The cytoplasmic membrane plays a crucial role in generating energy (ATP) for the cell.

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    What is the cell wall?

    A thick, protective layer outside the cytoplasmic membrane, providing structural support and resisting osmotic pressure.

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    Budding

    The process by which a yeast cell develops a protuberance that grows and separates to create a new cell.

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    What is a capsule?

    A sticky, protective layer that surrounds the cell, often composed of polysaccharides or polypeptides.

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    What is one important function of a capsule?

    Capsules help bacteria evade the immune system by preventing phagocytosis, the process by which immune cells engulf and destroy bacteria.

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    Besides evading the immune system, what else can capsules do?

    Capsules help protect the bacterial cell wall from attack by substances like bacteriophages, lysozyme, and antibiotics.

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    What are flagella?

    Long, whip-like structures that allow bacteria to move.

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    What are the parts of a flagellum?

    Flagella consist of three parts: the filament, hook, and basal body.

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    What are fimbriae or pili?

    Short, hair-like structures that help bacteria attach to surfaces.

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    What are the types of fimbriae?

    Fimbriae can be classified into two types: ordinary fimbriae and sex pili.

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    What is the function of ordinary fimbriae?

    Ordinary fimbriae help bacteria attach to surfaces, contributing to their ability to colonize environments.

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    What is the function of sex pili?

    Sex pili are involved in the transfer of genetic material between bacteria during conjugation.

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    Describe the cytoplasm.

    The gel-like interior of a bacterial cell, containing ribosomes, enzymes, and other molecules involved in cellular processes.

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    What are ribosomes?

    Small, dense structures in the cytoplasm that are responsible for protein synthesis.

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    What is the bacterial chromosome?

    The single, circular chromosome of DNA found in bacteria, carrying the genetic information for the cell.

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    Study Notes

    Bacterial Morphology and Structure

    • Bacteria are prokaryotic microorganisms, small in size (0.2µm-1.5µm diameter, 3µm-5µm length)
    • Morphology describes shape, size, and arrangement
    • Bacterial shapes include:
      • Cocci: spherical (e.g., Staphylococcus, Streptococcus)
      • Bacilli: rod-shaped (e.g., coccobacilli)
      • Vibrios: curved or comma-shaped
      • Spirilla: rigid spiral
      • Spirochetes: flexuous spiral (e.g., Campylobacter)
      • Mycoplasma (pleomorphic): cell wall-deficient, irregular shapes

    Bacterial Arrangement

    • Cocci arrangements vary based on division planes:
      • Diplococci: pairs
      • Chains: repeated divisions in one plane
      • Clusters: divisions in random planes
      • Tetrads: groups of four
      • Packets: groups of eight
    • Bacilli arrangements are limited, often in chains (streptobacilli)

    Bacterial Cell Envelope

    • Outer layer consisting of:
      • Cell wall: rigid, permeable layer (10-25nm thick)
        • Gives shape and rigidity, supports cytoplasmic membrane, maintains shape, involved in division and interactions with other cells or mammalian cells. Provides receptors for some bacterial viruses.
        • Composed of peptidoglycan (mucopeptide/murein): alternating N-acetyl glucosamine and N-acetyl muramic acid linked by peptide bonds. Different cross-bridges and tetrapeptide chains vary by species.
      • Cytoplasmic (plasma) membrane: thin (5-10nm), elastic, lies beneath cell wall, controls metabolite flow, houses enzymes for synthesis, energy generation (ATP), and motility, mediates chromosomal segregation

    Gram-Positive vs. Gram-Negative Cell Walls

    • Gram-positive walls: simpler, thicker peptidoglycan layer (50-90% dry wall weight), also contain teichoic acids (glycerol/ribitol + phosphate)
    • Gram-negative walls: more complex, thinner peptidoglycan layer (5-10% dry wall weight), contains lipoprotein, outer membrane, and lipopolysaccharide (LPS). LPS is a large complex molecule (lipid A, core polysaccharide, O polysaccharide).
    • Outer membrane acts as a protective barrier (prevents toxic substance entry) through porins (transmembrane proteins)

    Bacterial Appendages

    • Capsule/Slime Layer: extracellular polymer, protects against phagocytosis, cell wall attack, used in bacterial identification and typing.

    • Flagella: long, helical filaments (flagellin protein), allow motility, with filament, hook, and basal body components. Basal body has different ring structures depending on type (gram + or gram -)

    • Fimbriae/Pili: short, hair-like appendages, adhesion, and transfer of genetic material (sex pili). Sex pili facilitate conjugation, the transfer of genetic material from one bacteria to another.

    Bacterial Cell Interior

    • Cytoplasm: viscous solution with organic/inorganic solutes, ribosomes, and no internal structures seen in eukaryotes.
    • Ribosomes: 70S (30S + 50S), site of protein synthesis, smaller than eukaryotic ribosomes (80S). Components include mRNA, rRNA, tRNA.
    • Mesosomes (chondroids): invaginations of plasma membrane, involved in DNA compartmenting, site of some respiratory enzymes in bacteria analogous to mitochondria in eukaryotes.
    • Intracellular Inclusions: storage bodies (volutin/polyphosphate, lipid, glycogen, starch).
    • Bacterial Nucleus: single circular DNA molecule, haploid, replicates through simple fission, not membrane-bound.

    Fungi

    • Eukaryotic, spore-bearing, lacking chlorophyll, absorptive nutrition.

    • Mycology: study of fungi.

    • Growth forms (Yeasts and Molds)

      • Yeasts: unicellular, asexual reproduction (budding/fission)
      • Molds: filamentous, hyphae form a mycelium, septate/non-septate
    • Fungal cell wall is a complex structure providing support, protection, and maintaining cellular shape. It's composed of chitin and other polysaccharides.

    • Types of fungal spores:

      • Sexual: oospores, ascospores, zygospores, basidiospores formed during meiosis.
      • Asexual: vegetative (blastospores, arthrospores, chlamydospores) and aerial (conidia, microconidia, macroconidia), sporangiospores.
    • Dimorphic Fungi: two forms (yeast or mold) depending on environmental conditions (eg: temperature); change from Y (yeast) to M (mold) is called YM shift.

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    Test your knowledge on the morphology and structure of bacteria, including their shapes, arrangements, and cell envelopes. This quiz covers essential characteristics of different bacterial types and their classification. Perfect for microbiology enthusiasts and students!

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