How do cells move things in and out of the cell?? Cell Transport Methods 1.Passive Transport —Diffusion, Osmosis and Facillatated Diffusion 2.Active Transport---

How do cells move things in and out of the cell?? Cell Transport Methods 1.Passive Transport Diffusion, Osmosis and Facillatated Diffusion 2.Active Transport--- Endocytosis, Exocytosis, and Protein Pump Passive Transport When a cell uses no energy to move particles across a membrane passive transport occurs Particles go DOWN their concentration gradient. Diffusion & osmosis are passive transport. Concentration gradient Plasma membrane Diffusion Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration.(down a concentraion gradient) In a cell, water always moves to reach an equal concentration on both sides of the membrane. This is called Equilibrium Osmosis: Diffusion of Water The diffusion of water across a selectively permeable membrane is called osmosis. Regulating the water flow through the plasma membrane is an important factor in maintaining homeostasis(equilibrium) within a cell. What controls osmosis? Unequal distribution of particles, called a concentration gradient, is one factor that controls osmosis. Travels from high concentration to a low concentration Before Osmosis After Osmosis Selectively permeable membrane Water molecule Sugar molecule Passive Transport by proteins Passive transport of materials across the membrane using transport proteins is called facilitated diffusion. Channel proteins Concentration gradient Plasma membrane Passive Transport by proteins Some transport proteins, called channel proteins, form channels that allow specific molecules to flow through. Active Transport active transport :Movement of materials through a membrane against a concentration gradient and requires energy from the cell. Concentration gradient Carrier proteins Cellular energy Transport of Large Particles into the Cell Endocytosis is a process by which a cell surrounds and takes in material from its environment. The material is engulfed and enclosed by a portion of the cell s plasma membrane. resulting vacuole with its contents moves to the inside of the cell Exocytosis is the expulsion or secretion of materials from a cell. It is how materials are removed from the cell. Transport of Large Particles out of the Cell How active transport occurs with a protein pump. a transport protein called a carrier protein first binds with a particle of the substance to be transported. Each type of carrier protein has a shape that fits a specific molecule or ion. AC ONLY Types of Solutions Cells in an isotonic solution isotonic solution- ( Equal concentrations) the concentration of dissolved substances in the solution is the same as the concentration of dissolved substances inside the cell. H2OH2O H2OH2O Water Molecule Dissolved Molecule Cells in an isotonic solution water molecules move into and out of the cell at the same rate, and cells retain their normal shape. H2OH2O H2OH2O Water Molecule Dissolved Molecule Cells in an isotonic solution A plant cell has its normal shape and pressure in an isotonic solution. NO Shrinking or Swelling Cells in a hypotonic solution Hypo-means low hypotonic solution : dilute solution (More water than solute concentration) High water outside cell, low water inside cell In a hypotonic solution, water enters a cell by osmosis, causing the cell to swell. H2OH2O H2OH2O Water Molecule Dissolved Molecule Cells in a hypotonic solution Plant cells swell beyond their normal size as pressure increases. (plants prefer this it makes the leaves firm) However, an animal cell may swell and burst Cells in a hypertonic solution hyper means high hypertonic solution: concentrated solution, thus a high solute concentration Low water ratio outside cell, but high water ratio inside the cell In a hypertonic solution, water leaves a cell by osmosis, causing the cell to shrink H2OH2O H2OH2O Water Molecule Dissolved Molecule Cells in a hypertonic solution Plant cells lose pressure as the plasma membrane shrinks away from the cell wall. The cell will shrink in size, can become dehyrated and die. Examples