Term
Know why the plasma membrane called a fluid mosaic. |
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Definition
It is sometimes referred to as a fluid mosaic because it has many types of molecules which float along the lipids due to the many types of molecules that make up the cell membrane. |
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Term
Know the main component of the plasma membrane and their functions. |
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Definition
Components of the Plasma Membrane
§Three components:
1.Lipid component referred to as phospholipid bilayer
2.Protein molecules:
–Float around like icebergs on a sea
–Membrane proteins may be peripheral or integral
»Peripheral proteins are found on the inner membrane surface
»Integral proteins are partially or wholly embedded (transmembrane) in the membrane
3.Cholesterol affects the fluidity of the membrane |
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Term
Know why the plasma membrane is called selectively permeable. |
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Definition
§Selectively permeable:
•Allows some substances to move across the membrane
•Inhibits passage of other molecules. |
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Term
Know the terms on table 5.1 and what they mean. |
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Definition
| Print PowerPoint table 5.1 |
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Term
What is diffusion?
What is a concentration gradient?
What is passive diffusion? |
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Definition
1. Diffusion: is the tendency of particles to spread out evenly in an available space.
§Particles will move from an area of more concentrated particles to an area where they are less concentrated.
2. Concentration gradient: Move from an area of high concentration to an area of low concentration.
3. Passive diffusion: NO Energy is Required
§Net movement of moleculesdown a concentration gradient (from to concentration).
§Molecules move both ways along gradient, but net movement is always from high to low concentration.
§ Equilibrium: •When NET movement stops
•Solute concentration is uniform – no gradient. |
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Term
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Definition
•Osmosis: Special case of diffusion
§Focuses on solvent (water) movement rather than solute
§Diffusion of water across a selectively permeable membrane
1.Solute concentration on one side is high, but water concentration is low
2.Solute concentration on other side is low, but water concentration is high
§Movement of Water occurs when the water can diffuse both ways across membrane but the solute cannot
§Net movement of water is toward low water (high solute) concentration.
•Osmotic pressure is the pressure that develops due to osmosis
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Term
What does hypertonic mean?
Hypotonic?
Isotonic? |
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Definition
1. Hypertonic: Concentration of solute is higher in the solution than inside the cell.
§Cells placed in a hypertonic solution will shrink:
•Crenation in animal cells
•Plasmolysis in plant cells
2..Isotonic Solutions:
§Solute and water concentrations are equal on both sides of membrane
§No net gain or loss of water by the cell
3. Hypotonic: Concentration of solute in the solution is lower than inside the cell.
§Cells placed in a hypotonic solution will swell:
•Causes turgor pressure in plants
•May cause animal cells to lyse (rupture).
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Term
What happens to cells placed in the above solutions? |
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Definition
1. Cells placed in a hypertonic solution will shrink:
•Crenation in animal cells
•Plasmolysis in plant cells
2. Cells placed in a hypotonic solution will swell:
•Causes turgor pressure in plants
•May cause animal cells to lyse (rupture)
3. Cells placed in an isotonic solutions:
§No net gain or loss of water by the cell
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Term
Know how facilitated diffusion works.
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Definition
Passive Facilitated Diffusion
•Facilitated Transport – Needs Help
§Movement of molecules that cannot pass directly through the membrane lipids..
§These molecules must combine with channel or carrier proteins to move across the membrane.
§Still move down a concentration gradient, moving from high concentration to low concentration.
•Facilitated Diffusion – molecules enter the cell through a
§Protein CHANNEL
§Protein CARRIER |
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Term
Know the different types of active transport.
Know the example discussed in class.
What is exocytosis & endocytosis & the different types?
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Definition
3 main types of Active Transport:
1. Sodium-Potassium pump: Uses ATP to move sodium ions out of the cells and
potassium ions into the cell against their concentration gradients.
2. Exocytosis: Vesicles fuse with plasma membrane and secrete contents (Golgi apparatus).
3. Endocytosis: Cells engulf substances into a pouch which becomes a vesicle
•Phagocytosis: Large, solid material is taken in by endocytosis
•Pinocytosis: Vesicles form around a liquid or very small particles
•Receptor-Mediated Endocytosis: Specific form of pinocytosis using
receptor proteins and a coated pit
Macromolecules are transported into or out of the cell inside vesicles via bulk transport. |
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Term
What energy molecule is required for active transport?
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Definition
•Active Transport – Requires Energy
§The movement of molecules against their concentration gradient
•Movement from low to high concentration
§Movement is facilitated by carrier proteins
§Requires the expenditure of energy in the form of ATP (the cell energy molecule)
•Example: sodium-potassium pump
- Uses ATP to move sodium ions out of the cells and potassium ions into the cell against their concentration gradients. |
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Term
Know what the extracellular matrix is and its components. |
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Definition
Extracellular Matrix (ECM)
•Protective meshwork of proteins and polysaccharides in close connection with the cell that produced them:
–Collagen – resists stretching
–Elastin – provides resilience to the ECM
–Integrin – play role in cell signaling
–Proteoglycans – regulate passage of material through the ECM to the plasma membrane. |
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Term
Know the three types of cell junctions.
Know what type is present in plant cells. |
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Definition
§Junctions Between Cells
1. Adhesion Junctions: mechanically attach two adjacent cells with Intercellular filaments
•Desmosomes and hemidesmosomes (anchoring junctions) – internal cytoplasmic plaques
2.Tight Junctions (occluding junctions): form impermeable barriers
3.Gap Junctions (allows communication): Plasma membrane channels are joined |
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Term
Know the main component of the plasma membrane and their functions
Additional Structures. |
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Definition
Additional Structures
•Carbohydrate Chains:
§Glycoproteins - Proteins with attached carbohydrate chains
§Glycolipids - Lipids with attached carbohydrate chains
§These carbohydrate chains exist only on the outside of the membrane
§Functions: stabilize the membrane structure; act as receptors; help in cell identification; recognize foreign substances |
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Term
| Know the main functions of the plasma membrane Part1. |
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Definition
Functions of Membrane Proteins
§Channel Proteins: Allow passage of molecules through membrane via a channel in the protein.
§Carrier Proteins: •Combine with the substance to be transported
•Assist passage of molecules through membrane
§Cell Recognition Proteins:
•Glycoproteins – outside the cell
•Help the body recognize foreign substances
•Help the body recognize cells are being part of the body |
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Term
| Know the main functions of the plasma membrane Part 2. |
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Definition
Functions of Membrane Proteins P2.
§Receptor Proteins:
•Bind with specific molecules
•Allow a cell to respond to signals from other cells
§Enzymatic Proteins:
•Carry out metabolic reactions directly
§Junction Proteins:
•Attach adjacent cells
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Term
Membrane Protein Diversity |
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Definition
1. Channel Protein: Allows a particular molecule or ion to cross the
plasma membrane freely.
2. Carrier Protein: Selectively interacts with a specific molecule or ion so that it can cross the plasma membrane.
3. Cell Recognition Protein: The MHC (major histocompatibility complex) glycoproteins are different for each person, so organ transplants are difficult to achieve. Cells with foreign MHC glycoproteins are attacked by white blood
cells responsible for immunity.
4. Receptor Protein: Is shaped in such a way that a specific molecule can bind to it. Pygmies are short, not because they do not produce enough growth hormone, but because their plasma membrane growth hormone receptors are faulty and cannot interact with growth hormone.
5. Enzymatic Protein: Catalyzes a specific reaction. The membrane protein, adenylate cyclase, is involved in ATP metabolism. Cholera bacteria release a toxin that interferes with the proper functioning of adenylatecyclase; <span style="font-family: |
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Term
| Know the main functions of the plasma membrane Part 3. |
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Definition
Permeability of the Plasma Membrane:
§The plasma membrane is selectively permeable
•Allows some substances to move across the membrane
•Inhibits passage of other molecules.
§Small, non-charged (non-polar) molecules (CO2, O2, glycerol, alcohol) freely cross the membrane by passing through the phospholipid bilayer by diffusion
•These molecules follow their concentration gradient
–Move from an area of high concentration to an area of low concentration |
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Term
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Definition
Aquaporin: Are specialized proteins that speed up water transport across the membrane. |
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Term
What is a carrier protein? |
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Definition
Carrier proteins are proteins involved in the movement of ions, small molecules, or macromolecules, such as another protein, across a biological membrane.
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