Cell Theory and Structure
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Questions and Answers

What is the main characteristic that distinguishes Gram positive bacteria from Gram negative bacteria?

  • Cell shape
  • Response to Gram staining (correct)
  • Type of glycocalyx
  • Presence of a plasma membrane

    • Which part of a bacterial flagellum is considered the longest portion?

  • Hook
  • Filament (correct)
  • Plasma membrane
  • Basal body

    • Which statement about the glycocalyx is true?

  • It is uniform in composition across all bacteria.
  • It is always thick and tough.
  • It only serves a structural function.
  • It can be either a slime layer or a capsule. (correct)

    • What role do mesosomes play in bacterial cells?

    <p>Facilitate DNA replication and cell division</p> Signup and view all the answers

    What is the primary function of pili in bacteria?

    <p>Assist in attachment to surfaces</p> Signup and view all the answers

    Which of the following is not a primary component of the bacterial flagellum?

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

    What characteristic is true about the plasma membrane of bacteria?

    <p>It is selectively permeable.</p> Signup and view all the answers

    What structural feature distinguishes some cyanobacteria from other prokaryotes?

    <p>Presence of chromatophores</p> Signup and view all the answers

    What is the primary function of the rough endoplasmic reticulum?

    <p>Synthesis of proteins</p> Signup and view all the answers

    What role do centrioles play during cell division in animal cells?

    <p>They form the spindle apparatus</p> Signup and view all the answers

    Which part of the mitochondria is responsible for oxidative phosphorylation?

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

    Which organelle is involved in packing and transporting cell secretions?

    <p>Golgi complex</p> Signup and view all the answers

    What type of plastids are responsible for photosynthesis in plant cells?

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

    Who first explained that new cells are formed from pre-existing cells?

    <p>Rudolf Virchow</p> Signup and view all the answers

    What does the term 'eukaryotic cells' refer to?

    <p>Cells with a membrane bound nucleus</p> Signup and view all the answers

    Which of the following structures is found only in eukaryotic cells?

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

    What is the role of ribosomes in both prokaryotic and eukaryotic cells?

    <p>Synthesize proteins</p> Signup and view all the answers

    Which of the following is NOT a characteristic of the cell theory?

    <p>All cells contain chloroplasts</p> Signup and view all the answers

    What distinguishes prokaryotic cells from eukaryotic cells?

    <p>Lack of membrane-bound organelles</p> Signup and view all the answers

    Which organelle is specifically associated with animal cells and assists in cell division?

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

    What is the semi-fluid matrix found in both prokaryotic and eukaryotic cells called?

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

    What is the primary function of cilia?

    <p>To facilitate movement of the cell or surrounding fluid</p> Signup and view all the answers

    Which structural arrangement characterizes the axoneme of cilia and flagella?

    <p>9+2 array</p> Signup and view all the answers

    What are the basal bodies in relation to cilia and flagella?

    <p>They act as anchoring structures from which cilia and flagella emerge.</p> Signup and view all the answers

    How do flagella differ from cilia in terms of structure?

    <p>Flagella are longer and usually singular.</p> Signup and view all the answers

    What type of microtubule arrangement is found in the axoneme?

    <p>9 radially arranged doublets and 2 central microtubules</p> Signup and view all the answers

    What component connects the central tubules in the axoneme?

    <p>Interdoublet bridges</p> Signup and view all the answers

    Which statement is true about the flagella of prokaryotic bacteria compared to eukaryotic flagella?

    <p>Prokaryotic flagella differ structurally from eukaryotic flagella.</p> Signup and view all the answers

    What role do linkers play in the structure of cilia and flagella?

    <p>They interconnect peripheral doublets of microtubules.</p> Signup and view all the answers

    What is the structural arrangement of centrioles within a centrosome?

    <p>They lie perpendicular to each other.</p> Signup and view all the answers

    What is the composition of the peripheral fibrils of a centriole?

    <p>Nine triplets of tubulin protein.</p> Signup and view all the answers

    What role do centrioles play during cell division in animal cells?

    <p>They give rise to spindle apparatus.</p> Signup and view all the answers

    What is the hub in the proximal region of a centriole primarily composed of?

    <p>Protein.</p> Signup and view all the answers

    What did Robert Brown describe in 1831 that is crucial to cell function?

    <p>The nucleus.</p> Signup and view all the answers

    Study Notes

    Cell Theory

    • Formulated by Schleiden and Schwann, later modified by Rudolf Virchow.
    • Virchow introduced the concept that new cells arise from pre-existing cells ("Omnis cellula-e cellula").
    • Current cell theory includes:
      • All living organisms are composed of cells and their products.
      • All cells arise from pre-existing cells.

    Overview of Cell Structure

    • Onion and Cheek Cells:
      • Onion cells have a distinct cell wall and membrane; human cheek cells have an outer membrane.
      • Both cell types contain a nucleus housing chromosomes and DNA.

    Cell Types

    • Eukaryotic Cells:
      • Have membrane-bound nuclei and organelles (e.g., ER, Golgi complex, mitochondria).
    • Prokaryotic Cells:
      • Lack membrane-bound nuclei and organelles; have a simpler structure.

    Cytoplasm

    • A semi-fluid matrix in both cell types where chemical reactions necessary for cellular activities occur.

    Organelles

    • Eukaryotic Organelles:
      • Include various structures like mitochondria, lysosomes, and vacuoles.
      • Ribosomes are present in both eukaryotic and prokaryotic cells, found in cytoplasm and organelles.
    • Centrosome:
      • Contains centrioles that aid in cell division and are crucial for the formation of cilia and flagella.

    Bacterial Classification

    • Bacteria classified based on cell envelope differences; groups:
      • Gram-positive (stains) and Gram-negative (no stain).
    • Glycocalyx:
      • Varies in composition, may form a slime layer or thick capsule, aiding in structure and protection.

    Plasma Membrane and Mesosome

    • The plasma membrane is selectively permeable, allowing interaction with the environment.
    • Mesosomes, formed by plasma membrane extensions, play roles in respiration, secretion, and DNA distribution.

    Motility Structures

    • Flagella:
      • Present in motile bacteria, consisting of filament, hook and basal body.
      • Various arrangements and numbers affect bacterial motility.
    • Cilia:
      • Shorter than flagella, facilitate fluid movement or cell movement.

    Centrosomes and Centrioles

    • Each centrosome comprises two perpendicular centrioles, organized like a cartwheel.
    • Centrioles are essential for spindle formation during cell division.

    Nucleus

    • First described by Robert Brown; contains chromatin and nucleolus.
    • Regulates organelle activities and plays a major role in heredity.

    Endoplasmic Reticulum (ER)

    • Composed of rough (with ribosomes) and smooth (without ribosomes) regions.
    • Functions in protein synthesis and transport of substances.

    Golgi Complex and Lysosomes

    • Golgi Complex:
      • Membranous organelle for packaging and transporting cell secretions.
    • Lysosomes:
      • Contain digestive enzymes for macromolecule breakdown.

    Mitochondria and Plastids

    • Mitochondria:
      • Double-membrane organelles involved in ATP generation through oxidative phosphorylation.
    • Plastids:
      • Found in plant cells, with chloroplasts vital for photosynthesis (light reactions in thylakoids, dark reactions in stroma).

    Cellular Unit

    • The cell is the fundamental structural and functional unit of life, containing specialized organelles that perform specific functions.

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    Related Documents

    Chapter 8 Cell: The Unit of Life PDF

    Description

    Explore the fundamentals of cell theory and the structure of cells, including the distinctions between eukaryotic and prokaryotic cells. This quiz covers the contributions of Schleiden, Schwann, and Virchow, along with detailed insights into various organelles. Test your knowledge on cell components and their functions.

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