Bio 202 Chapter 7

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  1. Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. As a result, these lipid rafts
    A) are more rigid than the surrounding membrane. 
    B) have higher rates of lateral diffusion of lipids and proteins into and out of the lipid rafts.
    C) are more fluid than the surrounding membrane. 
    D) detach from the plasma membrane and clog arteries. 
    E) are able to flip from inside to outside.
    A) are more rigid than the surrounding membrane.
    (this multiple choice question has been scrambled)
  2. Singer and Nicolson's fluid mosaic model of the membrane proposed that
    membranes consist of protein molecules embedded in a fluid bilayer of phospholipids.
  3. Which of the following types of molecules are the major structural components of the cell membrane?
    phospholipids and proteins
  4. What are amphipathic molecules ?
    Amphipathic molecules have both hydrophobic regions and hydrophilic regions.
  5. According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?
    They can move laterally along the plane of the membrane.
  6. Describe the cholesterol effects on membrane fluidity at different temperatures
    • At WARM TEMP. cholesterol restrains movement of phospholipids.
    • At COOL TEMP. it maintain fluidity by preventing tight packing.
  7. What are the differences between integral protein and peripheral protein ?
    • Integral protein are found in the hydrophobic region and are usually called transmembrane protein
    • Peripheral Protein are bound to the surface of the membrane
  8. The primary function of polysaccharides (carbohydrates)  attached to the glycoproteins and glycolipids of animal cell membranes is to
    mediate cell-to-cell recognition.
  9. An animal cell lacking oligosaccharides on the external surface of its plasma membrane would likely be impaired in which function?
    cell-cell recognition
  10. What is a hydrophobic molecule?
    a non polar molecule such as hydrocarbon, carbon dioxide, and oxygen which can dissolve in the lipid bilayer and pass through the membrane rapidly.
  11. What kinds of molecules pass through a cell membrane most easily?
    small and hydrophobic
  12. What kind of molecules have difficulty passing through the cell membrane?
    Ions and polar molecules pass through with difficulty.This includes small molecules, like water, and larger critical molecules, like glucose and other sugars.
  13. What are transport proteins?
    • they allow the passage of hydrophilic substances across the membrane.
    • some transport proteins have a channel that certain molecules or ions can use as a tunnel through the membrane.
    • Others bind to these molecules and carry their passengers across the membrane physically.
  14. What is an aquaporine?
    Aquaporine is a channel protein that facilitates the passage of water.
  15. What is Passive transport?
    is the diffusion of a substance across a biological membrane where no energy is expended by the cell to make it happen.
  16. What is the difference between Hypertonic and Hypotonic solution ?
    • Hypertonic solution occurs when solute concentration is greater on the inside of the cell; cell loses water.
    • Hypotonic solution occurs when solute concentration is less than that inside the cell; cell gains water.
  17. what is facilitated diffusion ?
    The passive movement of molecules down its concentration gradient via a transport protein.
  18. What is Active Transport?
    Active transport occurs when transport proteins acts as a pump, moving substances across a membrane against their concentration gradients.It also requires energy in the form of ATP.
  19. Define Cotransport?
    A single ATP-powered pump that transports one solute which also can indirectly drive the active transport of several other solutes.
  20. Define  electrochemical gradient ?
    electrochemical gradient drives  the diffusion of ions across a membrane by a chemical force based on an ion’s concentration gradient and An electrical force based on the effect of the membrane potential on the ion’s movement.
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Bio 202 Chapter 7
2013-03-13 01:43:04

bio 202 chapter 7
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