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Transcript
Cellular Transport Notes Cell Membrane Outside of cell Proteins Carbohydrate chains Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer Cell Parts that are tested frequently: nucleus cytoplasm DNA chloroplast ribosomes mitochondria Cell membrane Cell Membrane Function of the Cell Membrane: 1. Lets things go in/out of the cell in order to maintain-regulator- selectively permeable: • Homeostasis • Balance • equilibrium 2. Recognizes other cells 3. Holds cytoplasm in the cell How the cell membrane moves things across the membrane and maintains a balance in the cell How Cell Membrane Works No Energy (HL) Diffusion -movement of SMALL molecules (solutes) H L How Cell Membrane Works No Energy (HL) Osmosis- the diffusion of water through a selectively permeable membrane by way of aqua-porins. H L Semi-permeable membrane is permeable to water, but not to sugar Practice: Osmosis #1 Osmosis is diffusion of water, therefore, we look at the concentrations of water. H L 100% water 0% salt 10% salt 90% water swell Practice: Osmosis #2 ON YOUR OWN Osmosis is diffusion of water, therefore, we look at the concentrations of water. L 80% water 20% salt H 10% salt 90% water Practice: Osmosis #3 ON YOUR OWN In equilibrium… 10% salt 90% water 10% salt 90% water But do the water molecules just stop moving? No. They move in/out at an equal rate. EQUILIBRIUM! Practice: Osmosis Salt water fish in fresh water. What will happen to the fish? H L Fish cells will gain water and swell Practice: Osmosis Fresh water fish in salt water. What will happen to the fish? L H Fish cells will lose water and shrink Hypertonic Solutions: contain a high concentration of solute relative to another solution. When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to shrivel/shrink. Hypotonic Solutions: contain a low concentration of solute relative to another solution. When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to swell and possibly explode/burst. Isotonic Solutions: contain the SAME concentration of solute as another solution. When a cell is placed in an isotonic solution, the water diffuses into and out of the cell at the same rate. Diffusion (molecules) Across Membranes 1. Diffusion 1. Facilitated diffusion Substances move with the concentration gradient from high to low, but carrier molecules speed up the movement of diffusing substances. No energy is required. 2. Active transport The movement of materials against the concentration gradient from low to high concentrations. Energy is required. Click • Endocytosis and Exocytosis is the mechanism by which very large molecules (such as food and wastes) get into and out of the cell Food is moved into the cell by Endocytosis Wastes are moved out of the cell by Exocytosis Ex: White Blood Cells, which are part of the immune system, surround and engulf bacteria by endocytosis. Sodium-Potassium Pump • A chemical mechanism that uses carrier proteins and energy to move 3 sodium ions out of the cell and 2 potassium ions into the cell. • The sodium potassium pump is important for the conduction of nerve impulses and contraction • of The sodium-potassium pump can transport 450 sodium and 300 muscles. potassium ions in and out of the cell in just one second. • 1/3 of an animal’s at rest energy is used to power the sodiumpotassium pump!