Chapter 12 - Membranes

Chapter 12 Membranes


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Terms to Know in This Chapter:

cell membrane (sing.)

plasma membrane (sing.) [PLAZ mah]

phospholipid [FOSS foe lip id]

bilayer

polar

nonpolar

fluid mosaic [moe ZAY ik]

glycocalyx [GLY co CAY licks]

proteins

dynamic [die NAM ik]

concentration gradient [con sin TRAY shun] [GRADE ee ent]

diffusion [deh FUSE shun]

osmosis [os MOE siss]

osmotic pressure [os MOTT ik]

facilitated diffusion [fah SILL ee tate ed]

passive transport

active transport

endocytosis [IN doe cy TOE siss]

exocytosis [EX oh cy TOE siss]

temperature

pressure

charge on particle

particle size

concentration

denaturation [DEE nature ay shun]

selectively permeable membrane [PURR me ah bul]

carrier protein

ATP

endoplasm [IN doe plaz um]

ectoplasm [EK toe plaz um]

phagocytosis [FAG oh cy toe siss]

pinocytosis [PEE no cy toe siss]

clathrin [CLATH rin]

pits

microfilaments

sodium-potassium pump

isotonic [EYE so ton ink]

hypertonic [HIGH purr ton ik]

hypotonic [HIGH poe ton ik]

saline [SAY lean]

Ringer's solution

turgor [TURR gor]

plasmolysis [plaz MOLL eh siss]

crenolysis [cree NOL eh siss]

hemolysis [he MOLL eh siss]


What You Need to Know:


You should be able to:

  1. describe the fluid-mosaic model of the membrane as to structure and composition,
  2. explain the significance of the charge on the phosphate group of the phospholipid,
  3. explain what is meant by the term dynamic and how it applies to the cell membrane,
  4. explain the function of a glycocalyx,
  5. list five things that influence whether something will pass through a membrane or not,
  6. define the term selectively permeable in relation to cell membranes,
  7. name two types of transport across cell membranes,
  8. name three types of passive transport and explain each,
  9. name three types of active transport and explain each,
  10. describe which types of transport require ATP and may work against a concentration gradient,
  11. explain osmotic pressure,
  12. distinguish between pinocytosis and phagocytosis and give an example of each,
  13. explain the terms isotonic, hypertonic, and hypotonic and how they affect plant and animal cells i.e., plasmolysis, turgor, crenolysis, and hemolysis,
  14. explain what a saline and Ringer's solution are, and
  15. explain the significance of the sodium-potassium pump.

Exercises: Fill in the Blank.


  1. The cell membrane may best be described as a bilayer of with scattered in and about the bilayer.
  2. The cell membrane is meaning it is constantly changing.
  3. The is often a sugar/protein structure that serves as the cell recognition factor.
  4. List five things that will determine what will go through a cell membrane and what will not.
    a.
    b.
    c.
    d.
    e.
  5. Of those listed in Question # 4, which is probably the most important?
  6. The passage of particles from a region of higher concentration to a region of lower concentration is referred to as .
  7. The diffusion of water through a membrane is called .
  8. For diffusion to take place, there must be a gradient. Otherwise, we say the particles are in
  9. Three forms of passive transport are , and . The one that uses the denaturation of a protein to accomplish its task is .
  10. Three forms of active transport are , , and . The sodium-potassium pump is an example of which of the three types?
  11. This type of active transport results in the conversion of a gel to a sol and back to a gel: . This form is given the special name of which means "cellular eating."
  12. Pinocytosis is a form of and is often referred to as "cellular drinking."
  13. The protein that often forms the coated pits in pinocytosis is called .
  14. requires the expenditure of energy in the form of ATP and may work against a .
  15. Cells may be exposed to three types of environments: , , and .
  16. When the concentration of materials inside the cell is greater than the concentration of materials outside the cell, we say the cell is in a(n) environment. (isotonic, hypertonic, hypotonic)
  17. A saline solution or Ringer's solution is an example of a(n) environment.
  18. When the concentration of materials outside the cell is greater than the concentration of materials inside the cell, we say the cell is in a(n) environment. (isotonic, hypertonic, hypotonic)
  19. When you place a plant cell in a hypertonic environment, it will experience . On the other hand, when you place a plant cell in a hypotonic environment, the cell will experience . (plasmolysis or turgor)
  20. A red blood cell placed in a hypertonic environment will undergo while a red blood cell placed in a hypotonic environment will undergo . (crenolysis or hemolysis)

    Exercises. Multiple Choice. Select the best answer.

  2. Which of the following is a correct statement about permeability of membranes?
     (1) Particle size makes no difference.
     (2) Pressure can cause particles to go through a membrane.
     (3) There must be a concentration gradient for particles to pass through.
     (4) Low temperatures increase permeability.

    (5) More than one answer is correct.

     

  3. Which is a correct statement about cell membranes?
     (1) The cell membrane is a double layer of proteins with phospholipids scattered in and about.
     (2) Cell membranes are static.
     (3) No proteins are found between the lipid bilayer.
     (4) The cell recognition factor is called the glycocalyx.

    (5) None of these are correct.

     

  4. The form of transport that has a carrier molecule and requires energy is:
     (1) facilitated diffusion.
     (2) osmosis.
     (3) active transport.
     (4) endocytosis.

    (5) exocytosis.


  5. This type of transport may work against a concentration gradient.
     (1) active transport
     (2) endocytosis
     (3) exocytosis
     (4) sodium-potassium pump

    (5) more than one answer is correct


  6. When the concentration of water inside a plant cell is greater than outside the cell, the cell is:
     (1) in an isotonic environment.
     (2) in a hypotonic environment.
     (3) undergoing turgor.
     (4) undergoing plasmolysis.

    (5) more than one answer is correct.


  7. Crenolysis:
     (1) occurs in plant cells.
     (2) is due to hypotonic environments.
     (3) doesn't hurt the cell because the cell wall protects it.
     (4) occurs in all plant cells.

    (5) is none of these.


  8. Phagocytosis:
     (1) is called "cellular drinking".
     (2) results from a colloidal state.
     (3) is a form of passive transport.
     (4) does not require the expenditure of energy.

    (5) more than one answer is correct.


  9. The molecule that lines the pits during pinocytosis is called:
     (1) histone.
     (2) an enzyme.
     (3) clathrin.
     (4) a glycocalyx.

    (5) none of these.


    Multiple, Multiple Choice.

    Sometimes, you need to be able to think in more than one plane at a time. These questions are sometimes called multiple, multiple choice. You will use the "key" shown below to answer the the following questions.

    1. Osmosis may be defined as the diffusion of water through a membrane.
    2. Osmosis requires the expenditure of energy in the form of ATP.
    3. The glycocalyx is the cell recognition factor.
    4. Water concentration outside the cell is greater than inside in a hypertonic environment.
    5. Plant cells experience hemolysis in a hypotonic environment.

    1 and 2 are correct.
     1 and 3 are correct.
     1, 2 and 3 are correct.
     4 only is correct.
     all are correct.

    1. Red blood cells experience hemolysis in a hypertonic environment.
    2. Phosphate groups carry a negative 4 charge.
    3. The sodium potassium pump is an example of passive transport.
    4. Particle size is the most important factor in permeability of membranes.
    5. A cell membrane is composed of a double layer of proteins with phospholipids scattered in between.

    1 and 2 are correct.
     1 and 3 are correct.
     1, 2 and 3 are correct.
     4 only is correct.
     all are correct.


    1. Phagocytosis is an example of active transport.
    2. Endocytosis is an example of active transport.
    3. Pinocytosis is an example of active transport.
    4. Facilitated diffusion is an example of active transport.
    5. Exocytosis is an example of passive transport.

    1 and 2 are correct.
    1 and 3 are correct.
     1, 2 and 3 are correct.
     4 only is correct.
     all are correct.


    1. ATP is required to work against a concentration gradient.
    2. Pressure is a factor which may affect permeability.
    3. Clathrin coated pits are involved in diffusion.
    4. Plant cells may experience crenolysis.
    5. Plant cells experience turgor in a hypertonic environment.

    1 and 2 are correct.
    1 and 3 are correct.
     1, 2 and 3 are correct.
     4 only is correct.
     all are correct.


    1. Ghosts are the result of hemolysis in red blood cells.
    2. Plasmolysis occurs in plant cells when placed in a hypertonic environment.
    3. The passage of particles from a region of higher concentration to a region of lower concentration is called diffusion.
    4. Osmosis is a form of passive transport.
    5. The glycocalyx is primarily composed of various combinations of sugars.

    1 and 2 are correct.
    1 and 3 are correct.
     1, 2 and 3 are correct.
     4 only is correct.
     all are correct.