Vocabulary: selective permeability, amphipathic, fluid mosaic model, integral protein, peripheral protein, glycoprotein, glycolipid, transport proteins, aquaporins, channel protein, carrier proteins, diffusion, osmosis, concentration gradient, passive transport, active transport, tonicity, isotonic, hypertonic, hypotonic, plasmolysis, crenation, proton pump, exocytosis, endocytosis, phagocytosis, pinocytosis, receptor-mediated endocytosis, ligands
Objectives:
After attending lectures and studying the chapter, the student should be able to:
1. Describe the fluid-mosaic model of membrane structure.
2. Identify the following general structural components of the plasma membrane:
phospholipids
membrane proteins
glycolipids / glycoproteins
cholesterol
3. Show the molecular structure of phospholipids.
4. Define hydrophilic and hydrophobic and relate these conditions to the structure of
phospholipid molecules.
5. Explain how the amphipathic nature of molecules (with hydrophilic and hydrophobic
regions) form membranes.
6. State the structural difference between saturated and unsaturated fatty acids in phospholipids and their role in maintaining optimum membrane fluidity.
7. Explain the role of cholesterol in membranes in maintaining optimum membrane fluidity.
8. State two categories of membrane proteins.
9. Describe the amphipathic nature of integral membrane proteins.
10. Describe the extracellular matrix attached to the outside of the plasma membrane in animal
cells.
11. Describe the process of making new plasma membrane sections inside a cell.
12. List the major functions of the plasma membrane.
13. Describe the structure and function of the three major types of cell junctions in animal cells
(desmosomes, gap junctions, and tight junctions).
14. Describe the structure and function of plasmodesmata cell junctions between plant cells.
15. Describe how associated membrane proteins can facilitate metabolic pathways.
16. State and describe the two types of cell signaling that are used to pass information through
the plasma membrane (without passing chemicals through the membrane).
17. Explain what is meant by: "The plasma membrane is selectively permeable."
18. Distinguish between the following mechanisms used by cells to transport substances across
the plasma membrane:
diffusion
protein-assisted transport
bulk transport
19. Relating to diffusion:
a. Define diffusion.
b. State which chemical substances can diffuse directly through the plasma membrane and
which substances cannot.
c. Distinguish between a concentration gradient, a charge gradient, and an electrochemical
gradient.
20. Relating to facilitated diffusion:
a. Define facilitated diffusion.
b. Define osmosis and describe the role of aquaporins in the movement of water into and
out of cells.
c. Distinguish between hypertonic, hypotonic, and isotonic aqueous solutions.
d. Relate solution tonicity to crenation and lysis in animal cells and to plasmolysis in plant
cells.
e. Describe ion channel receptors, explain how they can be activated by signal molecules,
and give an example of this process in humans.
21. Relating to active transport:
a. Define active transport.
b. Describe the proton pump.
22. Relating to bulk transport:
a. Define exocytosis and describe the process involving a Golgi vesicle.
b. Define endocytosis and distinguish between phagocytosis, pinocytosis, and receptor- mediated endocytosis.
| 2180411078 | selective permeability | a property of biological membranes that allows them to regulate the passage of substances across them |  | 0 |
| 2180411079 | amphipathic | having both a hydrophilic region and a hydrophobic region |  | 1 |
| 2180411080 | fluid mosaic model | the currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids. |  | 2 |
| 2180411081 | integral protein | a transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane (or lining the channel in the case of a channel protein). | 3 | |
| 2180411082 | peripheral protein | a protein loosely bound to surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer | 4 | |
| 2180411083 | transport protein | a transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane | 5 | |
| 2180411084 | aquaporin | a channel protein in the plasma membrane of a plant, animal or microorganism cell that specifically facilitates osmosis, the diffusion of free water across the membrane | 6 | |
| 2180411085 | diffusion | the spontaneous movement of a substance down its concentration or electrochemical gradient, from a region where it is more concentrated to a region where it is less concentrated. |  | 7 |
| 2180411086 | concentration gradient | a region along which the density of a chemical substance increases or decreases. | 8 | |
| 2180411087 | passive transport | the diffusion of a substance across a biological membrane with no expenditure of energy | 9 | |
| 2180411088 | osmosis | the diffusion of free water across a selectively permeable membrane | 10 | |
| 2180411089 | isotonic | referring to a soultion that, when surrounding a cell, causes no net movement of water into or out of a cell | 11 | |
| 2180411090 | hypertonic | referring to a solution that, when surrounding a cell, will cause the cell to lose water | 12 | |
| 2180411091 | hypotonic | referring to a solution that, when surrounding a cell, will cause the cell to take up water. |  | 13 |
| 2180411092 | osmoregulation | regulation of solute concentrations and water balance by a cell or organism | 14 | |
| 2180411093 | turgid | swollen or distended, as in plant cells. (A walled cell becomes turgid if it has a lower water potential then its surroundings, resulting in entry of water. | 15 | |
| 2180411094 | flaccid | lacking turgor (stiffness or firmness), as in the plant cell in surroundings where there is a tendency for water to leave the cell. ( A wall cell becomes flaccid if it has a higher water potential than its surroundings, resulting in the loss of water.) | 16 | |
| 2180411095 | plasmolysis | a phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment | 17 | |
| 2180411096 | facilitated diffusion | the passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins, requiring no energy expenditure. | 18 | |
| 2180411097 | ion channels | a transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient. | 19 | |
| 2180411098 | gated channels | a transmembrane protein channel that opens or closes in response to a particular stimulus | 20 | |
| 2180411099 | active transport | the movement of a substance across a cell membrane against its concentration gradient, mediated by specific transport proteins and requiring an expenditure of energy |  | 21 |
| 2180411100 | sodium-potassium pump | a transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell an potassium into the cell | 22 | |
| 2180411101 | proton pump | an active transport protein in a cell membrane that uses ATP to transport hydrogen ions out of a cell against their concentration gradient, generating a membrane potential in the process | 23 | |
| 2180411102 | cotransport | the coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient | 24 | |
| 2180411103 | exocytosis | the cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane. | 25 | |
| 2180411104 | endocytosis | cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane. | 26 | |
| 2180411105 | phagocytosis | a type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It's carried out by some protists and by certain immune cells of animals. | 27 | |
| 2180411106 | pinocytosis | a type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes | 28 | |
| 2180411107 | receptor-mediated endocytosis | the movement of specific molecules into a cell by the inward budding of vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances |  | 29 |
