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Cellular Transport Chapter 7.4 http://www.sciencephoto.com/media/117288/enlarge Cell Transportation • Materials needed for cellular processes must pass into cells so they can be utilized. • Waste materials from cellular processes must pass out of cells as they are produced. The Plasma Membrane • Regulates the passage of material into and out of the cell. • Depending on the needs of the cell, substances will move either in or out of the cell. • Because cells exist in a fluid environment, it is possible for substances to move in and out of the cell. Homeostasis • The necessity of an organism to maintain a constant or stable condition. • Dependent on appropriate movement of materials across the cell membrane. • All organisms have processes and structures which respond to stimuli in ways that keep conditions in their bodies conducive to life. Homeostasis • Maintained by the cell membrane. • The cell membrane is selectively permeable (semipermeable). • Materials can enter or exit the cell membrane by passive or active transport. Homeostasis • How do our cells maintain homeostasis? • 1)Passive Transport • 2)Active Transport http://nestbio.blogspot.com/2010/11/passive-and-active-transport.html Concentration Gradients • Molecules move in expected ways based on their concentration gradient. • At equilibrium, the concentration gradient is the same on both sides, so their is no movement. Passive Transport • Movement of any substance through the cell membrane. • Controlled by the cell membrane. • Does not require the use of energy. • Substances move with the concentration gradient. • HIGH TO LOW GO WITH THE FLOW Passive Transport: Diffusion • Process by which molecules spread across a cell membrane to reach an equal concentration (equilibrium). • Slow process dependent on concentration, temperature, and pressure. • Movement of small ions, atoms, gases, and molecules. • HIGH TO LOW GO WITH THE FLOW Diffusion • How Diffusion Works Animation http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_ diffusion_works.html Passive Transport: Osmosis • The diffusion of H20 through a selectively permeable membrane. • Water will move in and out of the cell until it reaches equilibrium. • Dependent on the concentration gradient. • HIGH TO LOW GO WITH THE FLOW Osmosis • How Osmosis Works Animation http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_ osmosis_works.html Passive Transport: Facilitated Diffusion • Substances that are not able to pass directly through the cell are able to enter the cell with the aid of transport proteins. • Occurs along a concentration gradient. • Ex) Glucose Facilitated Diffusion Proteins • Integral • Peripheral • Channel • Carrier • Marker • Receptor • Symports http://www.clker.com/clipart-49540.html Facilitated Diffusion • How Facilitated Diffusion Works Animation http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_f acilitated_diffusion_works.html Solutions Kool Aid Packet Solute Solvent Water Kool Aid Drink Solution Isotonic Solutions http://imcurious.wikispaces.com/Midterm+Exam+2010+Review+P2 Hypotonic http://spmbiology403.blogspot.com/2008/08/types-of-solution-hypotonic.html Hypertonic http://spmbiology403.blogspot.com/2008/08/types-of-solution-hypertonic.html Solutions http://biologyforlife.wordpress.com/2011/03/25/3-2-the-movement-of-substances-across-the-plasma-menbrane-in-everyday-life/ Active Transport • Cells pump molecules through the cell membrane and require energy. • Molecules move across the cell membrane against the concentration gradient (low to high). • Cells use this process to concentrate molecules within the cell or to remove waste from the cell. • Ex) Calcium, Sodium, and Potassium ions Active Transport: Proton Pump • Causes production of ATP molecules (energy). • Actively transports proteins through the membranes of mitochondria and chloroplasts. http://bioap.wikispaces.com/Ch+7+Collaboration+2010 Active Transport: + + Na /K Pump • Uses ATP to transport Na and K into and out of the cell. • Nerve cells use the difference in ion concentrations to send signals throughout your body. http://163.16.28.248/bio/activelearner/05/ch5c4.html Active Transport: Endocytosis and Exocytosis • When molecules are too large to pass through the cell membrane, the use of vesicles is required. • If the large molecule is passing into the cell it is called endocytosis. • If the large molecule is passing out of the cell it is called exocytosis. Endocytosis and Exocytosis http://thescienceupdate.blogspot.com/2010/09/may-force-be-with-you.html