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Transcript
What is the single most abundant compound in living organisms? A. fat B. water C. carbon D. sugar Answer: B #1-5 › Food › Light › Middle › Self › Up, throughout, again #6-10 › Carbohydrates › Nucleic Acids › Phospholipid bilayer › Proteins › Sugar, phosphate, nitrogenous base Complete the following: The cell membrane is composed of the __________________. The heads are ______________ and the tails are_____________. • What is energy? o Energy is the ability to do work. • What is potential energy? o Stored energy • What is kinetic energy? o Energy of motion Composed of the phospholipid bilayer Allows movement of certain substances into and out of the cell. Because the cell membrane is nonpolar, polar molecules, such as water, are unable to go through the cell membrane without going through a protein channel. • Passive Transport-substance crosses the cell membrane without any input of energy by the cell • Diffusion-takes place from an area of high concentration to an area of low concentration. • As a result of diffusion, the concentration of many types of substances eventually becomes balanced on both sides of a membrane. • Ex. the dispersal of ink in a beaker of water List all of the properties that make a reed diffuser (shown below) work. • Equilibrium-the concentration of molecules will be the same throughout the space the molecules occupy. • Concentration gradient-the difference in concentration of molecules across a distance. • High Concentration Low Concentration = Down (Passive) • Low Concentration High Concentration = Up (Active) • Simple diffusion-diffusion across the membrane • Osmosis-the process by which water passes into or out of a cell • Aqueous solution-a solution in which water is the solvent. • Osmosis • Hypotonic- the concentration of solute outside the cell is lower than the concentration inside the cytosol. • Hypertonic-the concentration of solute outside the cell is higher than the concentration in the cytosol. • Isotonic-the concentration of solutes outside and inside the cell are equal. • Osmosis Animation • Osmosis In 3 lines, explain what happens when a human drinks salt water. It is dangerous for humans to drink salt water because when you drink salt water, you put your cells into a hypertonic solution, so there is more salt on the outside of your cells than the inside. Water then leaves your cells & causes your cells to shrivel up, you go crazy and then you die. • When the solute concentration outside the cell is higher than that in the cytosol, the solution outside is hypertonic to the cytosol, and water will diffuse out of the cell. • When the solute concentration outside the cell is lower than the concentration in the cytosol, the solution outside is hypotonic to the cytosol, and water will diffuse into the cell. • When the solute concentrations outside and inside the cell are equal, the solution outside is isotonic, and there will be no net movement of water. • To remain alive, cells must compensate for the water that enters the cell in hypotonic environments and leaves the cell in hypertonic environments. • Contractile vacuoles are organelles that regulate water levels in paramecia. o o Is NOT a form of passive transport because it requires the cell to expend energy. Contractile vacuole • Turgor Pressure-the pressure that water molecules exert against the cell wall. • Plasmolysis-the cells shrink away from the cell walls, and turgor pressure is lost. • Cytolysis-the bursting of cells. • Egg Osmosis What characteristic of life means that you maintain a constant internal environment? Homeostasis-the maintenance of constant internal conditions Ex. Temperature, water content, uptake of nutrients by the cell Filtration-a type of passive transport involves the movement of water and solute molecules due to hydrostatic pressure Complete the following sentence: In a hypertonic solution, water will move ___________ a cell & in a hypotonic solution, water will move __________ a cell. In 3 lines, explain the difference between passive and active transport. • Facilitated Diffusion-the movement of large molecules across the cell membrane is assisted by specific proteins in the membrane. • Characteristics of facilitated diffusion: o o o It requires a carrier protein. It requires no energy input. It involves a change in the shape of its carrier. • Ex. Sugar molecules enter cells • Facilitated Diffusion • Carrier Proteins-the proteins that assist molecules across the cell membrane • Ion Channel-transport ions through the membrane • Ion Channel • Active Transport-materials move from an area of lower concentration, to an area of higher concentration. • Active transport systems are a form of cell transport that requires energy from molecules of ATP. • Active Transport • Allows a cell to stockpile substances in far greater concentrations than they occur outside the cell. • Some types of active transport are performed by carrier proteins called cell membrane pumps. • Ex. A calcium ion channel will allow only calcium ions to pass through it. • Sodium-Potassium Pump-transports Na+ & K+ ions up their concentration gradients • Usually pumps potassium into the cell. • Conduction of nerve impulses. • ATP supplies the energy that drives the pump • Sodium Potassium Pump • Pump • Some substances are too large to pass through the cell membrane by transport processes, so they must undergo endocytosis or exocytosis. • Molecules that are too large to be moved through the membrane can be transported into the cell by endocytosis. • Pinocytosis-“cellular drinking” • Phagocytosis-“cellular eating” o o Ex. Amoeba Amoeba Eating • Ridding the cell of material by discharging it from sacs at the cell surface. • Molecules that are too large to be moved across a cell membrane can be removed from the cell by exocytosis. • Exocytosis • Crash Course-Transport • Why is it dangerous for humans to drink ocean water? Cell Membrane Gummy Bear Labhttps://www.youtube.com/watch?v=HNT ymLy03gY