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Transcript
Name: Date: Per: Row: 7.3 Cell Boundaries A. Cell Membrane 1. Cell membrane- regulates what enters and leaves the cell and also provides protection and support. 2. ___________- double layered sheet that forms the core of nearly all cell membranes a. gives cell membranes a flexible structure that forms a barrier between the cell and its surroundings. 3. __________ molecules- embedded in the lipid bilayer to help move large molecules through the membrane, some of which have carbohydrate molecules attached to them 4. _______________ act like chemical identification cards, allowing cells to identify one another. 5. Fluid mosaic model- description of the cell membrane because there are so many kinds of molecules embedded in the membrane and it is constantly moving. Draw and label a phospholipid. Big Idea/Questions/Notes: Name: Date: Per: Row: Label the fatty acids and the phosphate molecule. Label which end is hydrophilic and hydrophobic. Hydrophilic= _______________ Hydrophobic= _____________ ↑ Label -Cell membrane -Carbohydrate chains -Outside of cell -Proteins -Inside of cell -Lipid bilayer B. Cell Wall 1. Cell wall- provides_________________________. a. are found in plants, algae, fungi, and many prokaryotes. 2. The cell wall lies outside the cell membrane. 3. Most cell walls are porous enough to allow water, oxygen, carbon dioxide, and certain other substances to pass through easily. C. Diffusion Through Cell Boundaries 1. Every living cell exists in a liquid environment. Big Idea/Questions/Notes: Name: Date: Per: Row: 2. The cell membrane regulates movement of dissolved molecules from the liquid on one side of the membrane to the liquid on the other side. D. Measuring Concentration 1. Solution- _____________________________________. 2. Solute- _______________________________________. a. Ex: salt or sugar 3. Solvent- the substance doing the dissolving. a. Ex: water 4. Concentration- of a solution is the mass of solute in a given volume of solution, or mass/volume. a. Ex: 12 grams of salt dissolved in 3 liters of water b. Solute= salt Solvent= water c. Concentration= 12 g/3 L or 4 g/L E. Diffusion 1. Diffusion- move from _______________ concentration. No energy required. 2. Equilibrium- when the concentration of the solute is the ___________ throughout a system Example: There is a higher concentration of solute on one side of the membrane as compared to the other side of the membrane. Solute particles move from the side of the membrane with a higher concentration of solute to the side of the membrane with a lower concentration of solute. The solute particles will continue to diffuse across the membrane until equilibrium is reached. Big Idea/Questions/Notes: Name: Date: Per: Row: When equilibrium is reached, solute particles continue to diffuse across the membrane in both directions. Draw an arrow showing the direction of “solute particle movement” below the beaker on the right. In the beaker on the right, draw and changes in water level or number of solute particles on each side of the membrane that occur as a result of the described process. F. Osmosis 1. ______________- the diffusion of water through a selectively permeable membrane. 2. Water diffuses from a highly concentrated region to a less concentrated region. 3. ____________- the more concentrated solution (“above strength”). 4. ___________- the more dilute solution (“below strength”). 5. ___________- concentrations of solutions are the same on both sides of a membrane (”same strength”) Big Idea/Questions/Notes: Name: Date: Per: Row: Draw an example of each type of solution; hypotonic, hypertonic, and isotonic. G. Osmotic Pressure 1. Osmosis exerts a pressure known as osmotic pressure on the hypertonic side of a selectively permeable membrane. 2. Because the cell is filled with salts, sugars, proteins, and other molecules, it will almost always be hypertonic to fresh water. 3. If so, the osmotic pressure should produce a net movement of water into the cell. As a result, the volume of the cell will increase until the cell becomes swollen or bursts. 4. Cells in large organisms are not in danger of bursting because they are bathed in fluids, such as blood, that are isotonic. 5. Other cells are surrounded by tough cell walls that prevent the cells from expanding even under tremendous osmotic pressure. H. Facilitated Diffusion 1. Cell membranes have protein channels that act as carriers, making it easy for certain molecules to cross. 2. Facilitated diffusion______________________________________________ Big Idea/Questions/Notes: Name: Date: Per: Row: ______________________________________________ ______________________________________________ 3. Although facilitated diffusion is fast and specific, it is still diffusion. 4. Facilitated diffusion will only occur if there is a higher concentration of the particular molecules on one side of a cell membrane as compared to the other side. I. Active Transport 1. Active transport______________________________________________ __________________________________________. 2. Active transport requires energy. Look at the diagrams. Label each as either facilitated diffusion or active transport. ~ Which process can move molecules from a lower concentration solution on one side of the membrane to a higher concentration solution on the other side. A: active transport ~ Which process does not require energy? A: facilitated diffusion Big Idea/Questions/Notes: Name: Date: Per: Row: J. Molecular Transport 1. Large molecules and even solid clumps of material may undergo active transport by means of the cell membrane. 2. Endocytosis- the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane. 3. The pocket breaks loose from the outer portion of the cell membrane and forms a vacuole within the cytoplasm. 4. Two examples of endocytosis are: a. ____________- extensions of cytoplasm surround a particle and package it within a food vacuole. The cell then engulfs it. i. requires a considerable amount of energy. b. ____________- tiny pockets form along the cell membrane, fill with liquid, and pinch off to form vacuoles within the cell. 5. ____________- the membrane of the vacuole surrounding the material fuses with the cell membrane, forcing the contents out of the cell. Big Idea/Questions/Notes: