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Transcript
7.3 CELL TRANSPORT CT Science Framework: Explain the role of the cell membrane in supporting cell functions. A. Cell membrane 1. Functions: a. protective barrier b. gives structure and shape c. regulates what enters and exits a cell A. Cell membrane ( cont.) 2. Structure of a. Double membrane of lipids -likes water ; repels waters b. Proteins are embedded within the layer Photograph of cell membrane The cell membrane is a fluid mosaic of lipids, proteins, and carbohydrates. FLUID- because the molecules move about ; like a liquid MOSIAC- because the proteins are scattered within the lipid layer B. Transport thru the cell membrane 1. Diffusion a. passage of materials across a space from an area of high concentration to an area of low concentration until an equilibrium is reached b. Concentration: the mass of a solute in a given volume of solvent (grams/liter) (example: 12 grams of salt in 3 liters of water-what is the concentration?) Diffusion (cont) c. Equilibrium: Concentration of a substance is the same across a space Diffusion (cont) Diffusion of a liquid d. Factors that affect diffusion P E ST S Permeability of the membrane Electrical charge of the substanceneutrally charged substances move easier Size of the molecule Temperature speeds up diffusion Solubility in water A Cell’s Environment is AQUEOUS ( water-based) Diffusion ( cont.) 2. Osmosis is a type of: a. Diffusion of water across a space from a point of high concentration to a point of low concentration b. Depends upon the concentration of a solute in a given volume of solvent which determines the type of cell solution Osmosis ( cont.) 3. CELL SOLUTIONS: a. Isotonic Solution: the amount of solute = the amount of solvent in and out of the cell Water moves in BOTH directions Isotonic Isotonic solution Osmosis Cont. b. Hypertonic Solution: Has a high concentration of solute vs. solvent Cells SHRINK because they lose water when placed in a hypertonic solution Example of hypertonic solution is salt water Hypertonic Hypertonic Solution Osmosis ( cont.) c. Hypotonic solution: Has a LOW concentration of solute vs. solvent Cells SWELL when placed in a hypotonic solution because they GAIN water Example: Fresh water Hypotonic Hypotonic Solution Solution Environments: Solution Environments: HYPERTONIC ISOTONIC HYPOTONIC 4. In other words…… a. In an isotonic solution….. -__________ happens to a cell, it looks the ___________ b. In a hypertonic solution……. -the cell _________ due to water ________ c. In a hypotonic solution…………. -the cell ________ due to water ________ 4. In other words…… a. In an isotonic solution….. -nothing happens to a cell, it looks the same b. In a hypertonic solution……. -the cell shrinks due to water loss c. In a hypotonic solution…………. -the cell swells due to water gain 5. Facilitated Diffusion The use of membrane proteins to help diffuse large particles ( eg-glucose, amino acids) across a cell membrane. Facilitated diffusion C. Passive Transport 1. Diffusion and osmosis are types of passive transport. a. Cell does not use energy to move a substance across the membrane/space. b. Cell energy is called ATP D. Active Transport 1. 2. 3. Energy (ATP) is required to move a substance across the membrane/space. Involves moving large materials into and out of cell. Types of -Endocytosis: move materials into a cell - Exocytosis: move materials out/exits of cell Endocytosis