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Anatomy & Physiology: Cell Structure and Function

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  • What is the functional unit of an organism?
    The cell is the functional unit of an organism, separated from its environment by the plasma membrane.
  • What are the three basic components of an animal cell?
    The three basic components are the plasma membrane, cytoplasm, and nucleus.
  • What is the difference between prokaryotic and eukaryotic cells?
    Prokaryotic cells are small and lack a nucleus (e.g., bacteria), while eukaryotic cells are larger and have a well-defined nucleus.
  • What is the plasma membrane and its main functions?
    The plasma membrane physically isolates the cell, provides structural support, regulates transport, communicates with other cells, and identifies the cell.
  • Describe the Fluid Mosaic Model of the plasma membrane.
    The plasma membrane is a flexible bilayer of phospholipids with various proteins floating in it, allowing lateral movement and dynamic function.
  • What are the main components of the plasma membrane?
    Phospholipids, proteins (integral and peripheral), cholesterol, and carbohydrates.
  • What is the structure and role of phospholipids in the membrane?
    Phospholipids form a bilayer with hydrophilic (water-loving) heads facing outward and hydrophobic (water-fearing) tails facing inward, creating a barrier.
  • What are integral and peripheral membrane proteins?
    Integral proteins span the membrane and are involved in transport and signaling; peripheral proteins attach loosely to the membrane surface and support cell shape and signaling.
  • Name the functions of membrane proteins.
    Functions include acting as channels, carriers, receptors, enzymes, structural support, and linking adjacent cells.
  • What role does cholesterol play in the plasma membrane?
    Cholesterol stabilizes membrane structure, maintaining fluidity by preventing it from becoming too rigid or too fluid with temperature changes.
  • What is the function of carbohydrates on the plasma membrane?
    Carbohydrates (glycolipids and glycoproteins) are involved in cell recognition and help cells identify each other.
  • What are the three types of membrane junctions?
    Tight junctions (seal cells), gap junctions (allow communication), and anchoring junctions or desmosomes (provide mechanical support).
  • What is the cytoplasm composed of?
    Cytoplasm includes cytosol (fluid), organelles (specialized structures), and inclusions inside the plasma membrane but outside the nucleus.
  • What is the cytoskeleton and its functions?
    The cytoskeleton is a protein filament network that provides cell shape, supports membranes and organelles, enables movement, and performs specialized functions.
  • Name the three types of cytoskeletal filaments.
    Actin filaments (microfilaments), intermediate filaments, and microtubules.
  • What are microvilli, cilia, and flagella?
    Extensions of the membrane: microvilli increase surface area; cilia move substances across cell surfaces; flagella propel cells through liquid.
  • What are organelles and their importance?
    Organelles are specialized structures within the cytoplasm that perform specific metabolic functions essential for cellular efficiency.
  • What is the function of mitochondria?
    Mitochondria produce most of the cell's ATP through oxidative catabolism and have their own DNA and ribosomes.
  • What is the role of peroxisomes?
    Peroxisomes detoxify chemicals, metabolize fatty acids, and synthesize certain phospholipids using oxidation reactions.
  • What is the function of ribosomes?
    Ribosomes synthesize proteins and can be free in the cytosol or bound to membranes.
  • Differentiate between rough and smooth endoplasmic reticulum (ER).
    Rough ER has ribosomes and modifies proteins; smooth ER lacks ribosomes, stores calcium, synthesizes lipids, and detoxifies substances.
  • What is the function of the Golgi apparatus?
    The Golgi apparatus sorts, modifies, packages proteins and other products from the ER for transport.
  • What are lysosomes and their functions?
    Lysosomes contain digestive enzymes that break down damaged organelles, ingested particles, and non-useful tissues.
  • What is the nucleus and its main components?
    The nucleus contains DNA, RNA, and proteins; components include the nuclear envelope, nucleoli, and chromatin.
  • Describe the nuclear envelope.
    A double lipid bilayer membrane with pores, continuous with the rough ER, that separates the nucleus from the cytoplasm.
  • What is chromatin?
    Chromatin is DNA wrapped around histone proteins forming nucleosomes, allowing DNA to be compacted inside the nucleus.
  • How does chromatin change during cell division?
    Chromatin condenses into chromosomes, which are tightly packed DNA structures visible during cell division.