AP Bio Chapter 7

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DesLee26
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48602
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AP Bio Chapter 7
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2010-11-09 22:19:28
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Cell Membrane
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Chapter 7
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  1. The membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the cell’s chemical composition
    plasma membrane
  2. The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids.
    fluid mosaic model
  3. A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.
    phospholipid
  4. A type of lipid characterized by a carbon skeleton consisting of four rings with various functional groups attached.
    steroid
  5. The plasma membrane is commonly described as a _____.
    Why???
    • fluid mosaic
    • It is like a mosaic in having diverse protein molecules embedded in a matrix of phospholipids.
  6. Its component proteins and phospholipid molecules can move about, causing the membrane to be what??
    fluid and flexible
  7. The phospholipids in a membrane form a two-layer framework called a _____. The steroid _____ helps stabilize the phospholipids. ______ are attached to some of the molecules that make up the membrane.
    • phospholipid bilayer
    • cholesterol
    • Carbohydrate molecules
  8. The ____________ of the bilayer is one reason membranes are selectively permeable.
    hydrophobic interior
  9. Having an aversion to water; tending to coalesce and form droplets in water.
    hydrophobic
  10. _________-- those that are soluble in lipids-- can easily pass through the membrane.
    Hydrophobic molecules
  11. In addition, what can small molecules like O2 do?
    sneak between the phospholipids of the membrane
  12. __ __ (like water and glucose) and ___ (such as sodium ions and hydrogen ions) cannot pass directly through the phospholipids of the plasma membrane. They must pass through specific __ ___ ___
    • hydrophilic molecules
    • ions
    • membrane transport proteins
  13. A transport protein in the plasma membrane forms a ___ through which water molecules or a specific solute can pass.
    channel
  14. Diffusion is the tendency for particles to move down their ____.
    concentration gradient
  15. The diffusion of a substance across a biological membrane.
    passive transport
  16. The diffusion of water across a selectively permeable membrane.
    osmosis
  17. In comparing two solutions, referring to the one with a greater solute concentration, causing the cell to shrink
    hypertonic
  18. Having the same solute concentration as another solution, resulting in neither shrinking nor swelling of the cell
    isotonic
  19. In comparing two solutions, referring to the one with a lower solute concentration, causing the cell to swell.
    hypotonic
  20. If water is not removed from an animal cell, what will happen to it?
    the pressure will exceed the tensile strength of the cell, and will burst open, or lyse.
  21. What prevents a plant cell from bursting?
    What is the desired effect of the plant?
    • plant cell wall
    • it should be turgid
  22. What occurs when a plant cell wall is exposed to a hypertonic environment?
    Plasmolysis
  23. The spontaneous passage of molecules and ions, bound to specific carrier proteins, across a biological membrane down their concentration gradients.
    facilitated diffusion
  24. A property of biological membranes that allows some substances to cross more easily than others.
    selective permeability
  25. Facilitated diffusion is a type of __ __, since the molecules are diffusing through the membrane and the cell expends no energy to move them.
    passive transport
  26. Sometimes a cell needs to move a solute against its concentration gradient. This process is called __ __, and it requires input of energy from __.
    • active transport
    • ATP
  27. The movement of a substance across a biological membrane against its concentration or electrochemical gradient with the help of energy input and specific transport proteins.
    active transport
  28. An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells.
    ATP
  29. How does ATP play a part in active transport?
    ATP transfers a phosphate group to the protein, providing the energy that causes the protein to change shape and push the ions across the membrane, where they are released outside the cell.
  30. The cellular uptake of macromolecules and particulate substances by localized regions of the plasma membrane that surround the substance and pinch off to form an intracellular vesicle.
    endocytosis
  31. The cellular secretion of macromolecules by the fusion of vesicles with the plasma membrane.
    exocytosis
  32. __ and __ are processes allow patches of membrane to flow from compartment to compartment, reminding us that a cell is a dynamic structure.
    • endocytosis
    • exocytosis
  33. ___ is the movement of intracellular vesicles to the plasma membrane, where they fuse with the membrane and release their contents into the surrounding fluid. This process occurs predominantly in __ __, such as mucus-producing cells or pancreatic cells, that secrete enzymes into the digestive tract.
    • Exocytosis
    • secretory cells
  34. In endocytosis, membranes ___, or pinch in, to form a vesicle, moving the enclosed materials inside the cell. This process can take different forms, each involving its own specific cell machinery.
    invaginate
  35. A type of endocytosis involving large, particulate substances, accomplished mainly by macrophages, neutrophils, and dendritic cells.
    phagocytosis
  36. In __, or "cell eating," the cell engulfs debris, bacteria, or other sizable objects.
    phagocytosis
  37. __ produces a __, which usually fuses with one or more __ containing hydrolytic enzymes. Materials in the vacuole are broken down by these enzymes and degraded.
    • Invagination
    • vacuole
    • lysosomes
  38. A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.
    pinocytosis
  39. In __, or "cell drinking," the cell engulfs extracellular fluid, including molecules such as sugars and proteins. These materials enter the cell inside a __. Epithelial cells in capillaries use this to engulf the liquid portion of blood at the capillary surface. The resulting vesicles travel across the capillary cells and release their contents to surrounding tissues, while blood cells remain in the blood.
    • pinocytosis
    • vesicle
  40. The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances.
    receptor-mediated endocytosis
  41. ___ is very specific. It is triggered when membrane receptors bind to specific external molecules, such as protein-cholesterol complexes or proteins bound to iron. Membrane vesicles pinch off, and the external protein and its cargo are brought into the cell.
    receptor-mediated endocytosis
  42. ___ is very specific. It is triggered when membrane receptors bind to specific external molecules, such as protein-cholesterol complexes or proteins bound to iron. Membrane vesicles pinch off, and the external protein and its cargo are brought into the cell.
    receptor-mediated endocytosis
  43. ___ is very specific. It is triggered when membrane receptors bind to specific external molecules, such as protein-cholesterol complexes or proteins bound to iron. Membrane vesicles pinch off, and the external protein and its cargo are brought into the cell.
    receptor-mediated endocytosis
  44. ___ is very specific. It is triggered when membrane receptors bind to specific external molecules, such as protein-cholesterol complexes or proteins bound to iron. Membrane vesicles pinch off, and the external protein and its cargo are brought into the cell.
    receptor-mediated endocytosis
  45. Which process is responsible for the uptake of iron in human cell?
    receptor- mediated endocytosis

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