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Transcript
Cell Transport It’s all about in and out. Passive Transport When a cell uses no energy to move particles across a membrane. Plasma membrane Concentration gradient Facilitated diffusion Passive transport of materials across the membrane using transport proteins. Channel proteins Plasma membrane Concentration gradient Facilitated diffusion Channel proteins form channels that allow specific molecules to flow through. Movement is with the concentration gradient, and requires no energy input from the cell. Channel proteins Plasma membrane Concentration gradient Facilitated diffusion Carrier proteins change shape to allow a substance to pass through the plasma membrane. Movement is with the concentration gradient and requires no energy. Carrier proteins Concentration gradient Plasma membrane Step 1 Step 2 Facilitated Diffusion Facilitated Diffusion Transport Proteins QuickTime™ and a Cinepak decompressor are needed to see this picture. Click image to view movie. Active Transport Movement of materials through a membrane against a concentration gradient; requires energy from the cell. Carrier proteins Plasma membrane Concentration gradient Cellular energy Step 1 Step 2 How active transport occurs QuickTime™ and a Cinepak decompressor are needed to see this picture. Click image to view movie. How active transport occurs A carrier protein binds with a particle. Each type of carrier protein has a shape that fits a specific molecule or ion. Carrier proteins Plasma membrane Concentration gradient Cellular energy Step 1 Step 2 How active transport occurs Chemical energy changes the shape of the carrier protein The particle is released on the other side of the membrane. Carrier proteins Plasma membrane Concentration gradient Cellular energy Step 1 Step 2 How active transport occurs Once the particle is released, the protein’s original shape is restored. Allows particle movement into or out of a cell against a concentration gradient. Carrier proteins Plasma membrane Concentration gradient Cellular energy Step 1 Step 2 Membrane Potentials Active transport can store energy by creating a difference in concentration of particles on each side. – Kind of like a battery. Membrane Potentials Uses: – Transporting other things – Making bonds – like during photosynthesis or cell respiration – Carrying signals – like in nerves Antiporter Symporter Transport of Large Particles Endocytosis is a process by which a cell surrounds and takes in material from its environment. Nucleus Wastes Digestion Endocytosis Exocytosis Transport of Large Particles The material is engulfed and enclosed by a portion of the cell’s plasma membrane. Nucleus Wastes Digestion Endocytosis Exocytosis Transport of Large Particles The resulting vacuole with its contents moves to the inside of the cell. Nucleus Wastes Digestion Endocytosis Exocytosis Transport of Large Particles Exocytosis is the expulsion or secretion of materials from a cell. Nucleus Wastes Digestion Endocytosis Exocytosis Amoeba Doing Endocytosis (Phagocytosis) Amoeba Doing Endocytosis (Phagocytosis) Amoeba Doing Endocytosis (Phagocytosis) Amoeba Doing Endocytosis (Phagocytosis) Amoeba Doing Endocytosis (Phagocytosis) Amoeba Doing Endocytosis (Phagocytosis) Amoeba Doing Endocytosis (Phagocytosis) Endocytosis http://biology.semo.edu/courses/bi190/ The formation of a membrane bound vacuole from cell membrane to enclose a particle and bring it inside the cell. QuickTime™ and a Sorenson Video decompressor are needed to see this picture. Click to Show Movie Exocytosis http://www.biology.washington.edu/bsa/IonTransport/exocytosis.html The process by which membrane material from a vacuole joins the cell membrane and expels the material the vacuole contained. QuickTime™ and a Animation decompressor are needed to see this picture. Click to Show Movie Pinocytosis Engulfing small particles and/or liquid. “cell drinking” Phagocytosis Engulfing large particles or organisms. “cell eating” Question 1 The diffusion of water across a selectively permeable membrane is called __________. Selectively permeable membrane A. active transport C. exocytosis Water molecule Sugar molecule B. endocytosis D. osmosis The answer is D, osmosis. Regulating the water flow through the plasma membrane is an important factor in maintaining homeostasis within the cell. Before osmosis Selectively permeable membrane After osmosis Water molecule Sugar molecule Question 2 What is the expected result of having an animal cell in a hypertonic solution? A. The cell shrivels up. B. The plasma membrane shrinks away from the cell wall. C. The cell swells up. D. The cell retains its normal shape. The answer is A. In a hypertonic solution, cells experience osmosis of water out of the cell. Animal cells shrivel because of decreased pressure in the cells. H2O H2O Water molecule Sugar molecule Question 3 A grocer mists the celery display with water to keep it looking fresh. What type of solution is the celery now in? A. isotonic B. hypotonic C. hypertonic D. exotonic The answer is B. Plant cells contain a rigid cell wall and do not burst even in a hypotonic solution. Question 4 Transport of materials across the plasma membrane that does not require energy from the cell but does use transport proteins is called __________. A. osmosis B. simple diffusion C. facilitated diffusion D. active transport Channel proteins Plasma membrane Concentration gradient The answer is C. Facilitated diffusion is a type of passive transport and requires no energy from the cell. Channel proteins Plasma membrane Concentration gradient