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Biology 3rd Block Room 128 Mr. R. Bair Biology Teacher Mrs. MV Smith Resource Teacher Date: October 5, 2007 Drill What did the onion cell do when it was exposed to salt water? It shriveled upo Why did it do this? Because the water was at a lower concentration outside the cell o Draw a picture illustrating what happened. What did the onion cell salt water do when it was exposed to DI water? It expanded back o Why did it do this? o Draw a picture illustrating what happened. Selectively Permeable Membrane- Membrane which allows some things to pass through but not all. Selective Permeable: a cell permits only certain substances-mainly oxygen, water, and food molecules to diffuse into the cell. Passive Transport: no energy required Diffusion- Movement of molecules from higher concentration to areas of lower concentration Diffusion: Molecules moving from high concentration to a low concentration movement from a high concentration to a low concentration until equilibrium is met Molecule Movement: temp up molecules move faster, cold temperature the molecules move slower. Concentration gradient The relation of two given areas, where the concentration of a particular substance differs between those areas. Diffusion will result in this substance moving along a concentration gradient until the concentration of the two areas becomes equal. This movement of concentration along a gradient is common in many biological processes, which are elaborated upon in the cell biology tutorial involving the biological cell which mentions the various ways how substances can pass through a cell membrane. http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html Good site for active and passive transport demonstration H L -Concentration=# of molecules in an area -Equilibrium=an even amount of molecules dye in water Biology 3rd Block Room 128 Mr. R. Bair Biology Teacher Mrs. MV Smith Resource Teacher high concentration movement low concentration Movement of molecules is random * Motion creates uniform distributions * Molecules move from regions of high concentration to low concentration * Molecules will passively move "down" a concentration gradient OsmosisDiffusion of water across a membrane. Never totally a full equilibrium 4) Osmosis -diffusion of water the flow of a solvent by diffusion through a semi-permeable membrane from a more concentrated solution to a less concentrated one, until the concentrations are equalized. It is a major factor in Brownian Movement: random movement of molecules or particles Solids: tight Liquids: a little spread out Biology 3rd Block Room 128 Mr. R. Bair Biology Teacher Mrs. MV Smith Resource Teacher Gases: very spread out Movement of the balloon around the room to represent an atom • • • 1. Hypertonic- Having a higher solute concentration Hypotonic- Having a lower solute concentration Homeostasis- Cell and it’s surroundings are at equilibrium V. Hypertonic, Hypotonic, Isotonic Hypertonic Solution i. Solute concentration in the environment is higher than that in the cell VI. In this diagram, the solution on the left side of the membrane has a higher solute concentration than the solution on the right side of the membrane. The solution on the left is said to be hypertonic compared to the one on the right. The higher solute concentration on the left reduces the flow of water molecules from left to right, causing a net flow of water from the right to the left. If the right side represented a cell placed in a hypertonic solution, water would leave the cell causing it to dehydrate and collapse. 2. HYPOTONIC SOLUTION a. Solute concentration in the environment is lower than in the cell In this diagram the solution on the left side of the membrane has a lower solute concentration than the solution on the right side of the membrane. The solution on the left is said to be hypotonic compared to the one on the right. The lower solute concentration on the left allows for increased flow of water molecules from left to right, causing a net flow of water from the left to the right. If the right side represented a cell placed in a hypotonic solution, water would enter the cell causing it to swell and perhaps burst. 3. Isotonic Solution a. A Solute CONENTRATION IN THE ENVIRONMENT THAT IS EQUAL TO THAT IN THE CELL. Biology 3rd Block Room 128 Mr. R. Bair Biology Teacher Mrs. MV Smith Resource Teacher An isotonic cellular environment occurs when an equal solute concentration exists inside and outside the cell. Molecules flow in and out at an equal rate by osmosis, causing the cell size to stay the same. It will not lose or gain any solutes. Plant cells in an isotonic environment are flaccid (they lack firmness) and they will wither. The equilibrium of water movement is unable to provide plant cells with internal pressure for structural support. An isotonic solution has an equal amount of dissolved solute in it compared to the things around it. Typically in humans and most other mammals, the isotonic solution is 0.9 weight percent (0.009 g/ml) salt in aqueous solution, this is also known as saline, which is generally administered via an intra-venous drip. It is a medium between hypotonic and hypertonic solutions. http://en.wikipedia.org/wiki/Isotonic Because the solute concentrations are the same on both sides of the membrane, water molecules move through the membrane equally well in both directions. There is no net flow of water in either direction. Osmosis: A special type of diffusion in which water moves from High to Low through a membrane. A semipermeable or differentially permeable membrane allows water or other small molecules to pass through because the openings in the membrane are of the proper size. If the molecules, like starches and proteins, are too large, they can't pass through. Label the fluid compartments of the following Red Blood Cells and watery environments. Use the terms: Hypotonic- Higher concentration of water, lower concentration of dissolved substances (solutes). Hypertonic- Higher concentration of dissolved substances, lower concentration of water. Isotonic- Equal effective concentration of water and solutes inside and outside the cell Salty & Fresh water fish Freshy is hypertonic Salty is hypotonic –swelling up III. Parts of a Solution a. Solute =item being dissolved b. Solvent=item doing the dissolving c. Solution=solvent + solute Passive transport-no energy required by the cell Diffusion fueled by Brownian Motion Active Transport- Transport, which requires energy (ATP) to take place Biology 3rd Block Room 128 Mr. R. Bair Biology Teacher Mrs. MV Smith Resource Teacher Factors which control what crosses the cell membrane 1. hydrophobic/Hydrophilic 2. too big-polysaccharides, big lipids, big proteins Facilitated Diffusion-Diffusion with the help of carrier molecules Endocytosis pinocytosis- cell drinking Phygocytosis-cell eating Exocytosis=using energy to remove items from the cell (cell vomiting) a vesicle out of the cell membrance i. Golgi Apparatus http://bio.winona.msus.edu/bates/chapter3.htm Biology 3rd Block Room 128 Mr. R. Bair Biology Teacher Mrs. MV Smith Resource Teacher