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5.1 Membrane Models
  • The present-day fluid-mosaic model proposes that membrane is less rigid and more dynamic than suggested by the previous sandwich model.
  1. Describe the fluid-mosaic model of the plasma membrane.
    Answer
Essential Study Partner Summaries of major points:
  1. Early observations
  2. In 1972, Singer and Nicolson introduced the currently accepted fluid-mosaic model of membrane structure.
5.2 Plasma Membrane Structure and Function
  • The plasma membrane regulates the passage of molecules and ions into and out of the cell.
  • The membrane contains lipids and proteins, each with specific functions.
  1. What is the difference between peripheral and integral proteins?
    Answer
  2. What is the glycocalyx and what are its functions?
    Answer
  3. List the five integral proteins found in the plasma membrane.
    Answer
Essential Study Partner Summaries of major points:
  1. Fluid-mosaic model
  2. Fluidity of the plasma membrane
  3. The membrane is a mosaic
Lab exercises
5.3 Permeability of the Plasma Membrane
  • Small, noncharged molecules tend to pass freely across the plasma membrane.
  • Some molecules diffuse (move from an area of higher concentration to an area of lower concentration) across a plasma membrane
  • Water diffuses across the plasma membrane and this can affect cell size and shape.
  • Carrier proteins assist the transport of some ions and molecules across the plasma membranes.
  • Vesicle formation takes other substances into the cell, and vesicle fusion with the plasma membrane discharges substances from the cell.
  1. What does it mean to be differentially permeable?
    Answer
  2. What are the similarities and differences between facilitated and active transport?
    Answer
  3. Can a solution always be considered hypotonic? Why or why not?
    Answer
  4. What types of molecules are moved into and out of cells via membrane assisted transport?
    Answer
Essential Study Partner Summaries of major points:
  1. Types of membranes and transport
  2. Diffusion and osmosis
  3. Transport by carrier proteins
Animation quizzes Art Quizzes Explorations Study Guides
  • Movement across membranes
  • Endocytosis and Exocytosis
Lab exercises
5.4 Modification of Cell Surfaces
  • In animals, the activities of cells within a tissue are coordinated in part because of junctions between the cells that allow them to communicate.
  • In animals, the extracellular matrix of cells influences their shape, movement, and function.
  • In plants, cells have a cell wall which supports the cell. The cell wall has plasmodesmata which permits passage of water and some solutes between cells.
  1. What are the functions of adhesion, tight and channel junctions between cells?
    Answer
  2. How do collagen and elastin fibers function in the extracellular matrix?
    Answer
  3. What are plasmodesmata and what is their function?
    Answer
Essential Study Partner Summaries of major points:
  1. Plasma membrane
  2. Plant cell walls
  3. Extracellular matrix of animal cells
  4. Junctions between cells
  5. Cell-cell recognition
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