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Published byCharlene York Modified over 9 years ago
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Section Objectives Explain how the processes of diffusion, passive transport, and active transport occur and why they are important to cells. Predict the effect of a hypotonic, hypertonic, or isotonic solution on a cell.
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Molecules move from high to low Diffusion – move from HIGH to LOW concentration
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Diffusion Move from HIGH to LOW concentration – passive transport – no energy needed diffusionosmosis diffusion of water
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Simple Diffusion Move from HIGH to LOW inside cell outside cell Which way will fat move? fat LOW HIGH
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Movement through the channel Why do molecules move through membrane if you give them a channel? ? ? HIGH LOW
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Facilitated Diffusion Move from HIGH to LOW through a channel inside cell outside cell sugar Which way will sugar move? sugar LOW HIGH
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Diffusion Move from HIGH to LOW concentration – directly through membrane simple diffusion no energy needed – help through a protein channel facilitated diffusion (with help) no energy needed HIGH LOW
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Simple vs. facilitated diffusion inside cell outside cell lipid inside cell outside cell H2OH2O simple diffusionfacilitated diffusion H2OH2O protein channel
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Passive Transport Requires no energy from cell Movement down the concentration gradient
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Facilitated Diffusion Cellular Structure and Function Movement of materials across the plasma membrane using protein channels.
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Osmosis Cellular Structure and Function Diffusion of water across a selectively permeable membrane Aquaporins are water channel proteins that allow water to pass through cell membrane through facilitated diffusion.
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Dynamic equilibrium is reached when the concentration
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Osmosis is the passive transport of water In osmosis, water travels from an area of lower solute concentration to an area of higher solute concentration –Hypertonic: [hyper=above, over] Solutions in which more solute present (concentrated solution) –Hypotonic: [hypo= below, under] Solutions in which less solute is present (dilute solution) –Isotonic: [ iso= equal] Solutions have equal concentrations of substances
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Blood Cell Plant Cell Isotonic Solution Cellular Structure and Function Water and dissolved substances diffuse into and out of the cell at the same rate. 11,397x
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Blood Cell Hypotonic Solution Cellular Structure and Function Solute concentration is higher inside the cell. Water diffuses into the cell. Plant Cell 13,000x
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Plant Cell Hypertonic Solution Cellular Structure and Function Solute concentration is higher outside the cell. Water diffuses out of the cell. Blood Cell 13,000x
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Water balance between cells and their surroundings is crucial to organisms Osmosis causes cells to shrink in a hypertonic solution and swell in a hypotonic solution –The control of water balance (osmoregulation) is essential for organisms ISOTONIC SOLUTION HYPOTONIC SOLUTION HYPERTONIC SOLUTION ANIMAL CELL PLANT CELL
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Active transport [ATP]Requires the cell to spend energy [ATP] Transport proteins can move solutes across a membrane against [up] a concentration gradient
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Active Transport Cellular Structure and Function Movement of particles across the cell membrane using energy Active Transport Using Carrier Proteins
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Active Transport active transport :Movement of materials through a membrane against a concentration gradient and requires energy from the cell. ATP Concentration gradient Plasma membrane Carrier proteins Cellular energy
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Active transport Cells may need molecules to move against concentration “hill” – need to pump “uphill” from LOW to HIGH using energy – protein pump – requires energy ATP
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Exocytosis and endocytosis transport large molecules 1. Exocytosis [ exo = outside] movement of large materials OUT of the cell ~a vesicle may fuse with the membrane and expel its contents CYTOPLASM FLUID OUTSIDE CELL
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2. Endocytosis [ endo = inside] movement of large materials to INSIDE of the cell ~membrane may fold inward, trapping materials from the outside
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