Skip to main content
뒤로

Anatomy & Physiology: Cell Structure and Membrane Function

컨트롤 버튼이 '내비게이션' 모드로 변경되었습니다.
1/20

이 집합의 용어 (20)

  • What are the three basic parts of a generalized cell?
    Plasma membrane (flexible outer boundary), cytoplasm (intracellular fluid + organelles), and nucleus (DNA-containing control center).
  • What is the plasma membrane composed of?
    A phospholipid bilayer with cholesterol and membrane proteins, forming a fluid mosaic where proteins float in a viscous lipid bilayer.
  • What is the role of the glycocalyx on the plasma membrane?
    The glycocalyx is a carbohydrate coating that enables cell recognition and communication.
  • Describe the polarity of phospholipid heads and tails in the plasma membrane.
    Phosphate heads are hydrophilic (polar, face water inside and outside the cell), and fatty acid tails are hydrophobic (nonpolar, face inward away from water).
  • What is the function of cholesterol in the plasma membrane?
    Cholesterol (~20%) increases membrane stability and controls fluidity.
  • Name the two main types of membrane proteins and their general functions.
    Integral proteins (transmembrane) and peripheral proteins; functions include transport, receptors, enzymes, cell junctions, and anchors.
  • List six functions of membrane proteins.
    Transport, signal transduction, attachment to cytoskeleton and extracellular matrix, enzymatic activity, intercellular joining, and cell-cell recognition.
  • What are the three types of cell junctions and their functions?
    Tight junctions (impermeable seals), desmosomes (anchoring junctions resisting stress), and gap junctions (communication channels for ions and small molecules).
  • How do tight junctions function in tissues?
    Integral proteins fuse to form an impermeable seal that prevents molecules from passing between cells, forcing absorption through cells.
  • What is the role of desmosomes?
    Desmosomes anchor cytoskeletons of adjacent cells, interlocking like a zipper to prevent cells from tearing apart.
  • What is the function of gap junctions?
    Gap junctions allow ions and small molecules to pass directly between cells, enabling communication, especially in excitable tissues like the heart.
  • What determines selective permeability of the plasma membrane?
    The lipid bilayer's hydrophobic core restricts polar and large molecules; small nonpolar molecules pass easily, while polar molecules require protein channels.
  • Differentiate between passive and active membrane transport.
    Passive transport requires no energy and moves substances down their concentration gradient; active transport requires ATP to move substances against the gradient.
  • What are the three types of passive transport?
    Simple diffusion (lipid soluble), facilitated diffusion (water soluble), and osmosis (water movement).
  • Describe simple diffusion across the plasma membrane.
    Unassisted movement of small, nonpolar, lipid-soluble molecules like O₂ and CO₂ from high to low concentration.
  • How does carrier-mediated facilitated diffusion work?
    Protein carriers bind large, lipid-insoluble molecules and change shape to transport them down their concentration gradient without energy.
  • What is channel-mediated facilitated diffusion?
    Ions and small polar molecules pass through protein channels (leak or gated) down their concentration gradient.
  • Explain osmosis in terms of water movement.
    Water moves through a semipermeable membrane from an area of low solute concentration (high water concentration) to high solute concentration (low water concentration).
  • Define isotonic, hypertonic, and hypotonic solutions in relation to cells.
    Isotonic: no net water movement; hypertonic: cells shrink as water leaves; hypotonic: cells swell as water enters.
  • What is the function of the Na⁺/K⁺ pump?
    It uses ATP to pump 3 Na⁺ out and 2 K⁺ into the cell, maintaining essential ion gradients for resting membrane potential and secondary transport.