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EQ: Can I diagram diffusion of oxygen, facilitated diffusion of glucose, and osmosis across a cell membrane? BOUNDARY OF THE CELL Cell: smallest unit that can carry out all the activities for life. (the “atom” of biology) Cell Membrane Outside of cell Carbohydrate chains Proteins Cell membrane Protein channel Lipid bilayer Inside of cell (cytoplasm) Membrane structure Semi-Permeable—certain molecules can pass through the membrane, but not all molecules can Fluid Mosaic Model— Proteins “float” in a fluid or moveable layer of phospholipids The Structure of the Cell Membrane Outside of cell Proteins Carbohydrate chains Cell membrane Inside Protein of cell channel (cytoplasm) Lipid bilayer • Phospholipid bilayer— Proteins—act as channels or pumps to help molecules through • phospholipids have a phosphate head (yellowpass circle) the membrane • lipid tails (the brown tails). Carbohydrate chains—help recognize and because communicate with • The phosphates linecells up on the outside they are each otherhydrophilic (water-loving). • The lipid tails line up on the inside because they are hydrophobic (water-hating). Review of solution terms: Solution – mixture of solute and solvent Solute – substance being dissolved Solvent – substance dissolving solute (Universal Solvent)-Water Membrane traffic Passive transport~ diffusion of a substance across a biological membrane (NO ENERGY) [] = concentration Diffusion~ the overall movement of particles from a region of high [] to an area of low [] Osmosis~ the diffusion of water across a selectively permeable membrane Results of Diffusion Dynamic equilibrium Once diffusion has evenly distributed the solute throughout the solvent; movement of particles continues with no change in [] Homeostasis Preservation of equilibrium Diffusion depends on [] gradient [] gradient: the difference in [] of a substance across space Diffusion is said to move down a [] gradient Diffusion continues until there is NO [] gradient Ex: O2 diffuses into oxygen depleted blood Diffusion molecules like WATER, OXYGEN, AND CARBON DIOXIDE can move in and out freely. Small Large molecules like PROTEINS AND CARBOHYDRATES CANNOT Charged IONS CANNOT QuickTime™ and a Cinepak decompressor are needed to see this picture. Osmosis~ the diffusion of water across a selectively permeable membrane Osmosis in the Real World Bryophytes, or mosses, are plants that depend on osmosis transfer water from the environment into the plant. Bryophytes can never grow tall, because they cannot pull the water against gravity just using the concentration gradient. Bryophytes must also live in wet environments Questions Osmosis is the diffusion of _______ across a cell membrane. Osmosis and Diffusion are both types of __________ transport. Passive transport does or does not require energy? Small molecules can not move across freely. T or F Large molecules can move freely. T or F Three Different Types of Solutions Isotonic Solution Hypotonic Solution Hypertonic Solution Isotonic Solution The solute outside the cell is equal in concentration to the solute in the cell. The cell retains its shape. water moves equally in both directions Hypotonic Solutions Solution outside the blood cell contains a lower [] of solute than inside of the cell. Water will diffuse in. cell will lyse (burst). Animal cells - cytolysis. Plant cells do not burst- turgur pressure— grocers use this idea Cells in a Hypotonic Solution Hypertonic Solutions The solution outside the cell has a higher [] of solute than inside of the cell. Water will diffuse out of the cell, causing the cell to shrink or crenate Why should you not salt meat before cooking? CRENATION PLASMOLYSIS Cells in a Hypertonic Solution In what type of solution would these cells be found? Water Balance Summary Osmoregulation~ control of water balance Hypertonic~ higher concentration of solutes Hypotonic~ lower concentration of solutes Isotonic~ equal concentrations of solutes Plasmolysis Turgidity in plant cells. QuickTime™ and a Cinepak decompressor QuickTime™ and a are needed toCinepak see thisdecompressor picture. are needed to see this picture. What type of solution is this? Hypertonic What will happen to the cell? It will shrink.
