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Types of Transport Types of Transport Across Cell Across Cell MembranesMembranes
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Passive Transport
▪ Does not require energy▪ Substances move from high to low▪Solutes move down the concentration gradient ▪Examples: oxygen, water, carbon dioxide
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Types of Passive Transport
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DiffusionDiffusion
▪Movement of substances (except water) across a cell membrane
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Diffusion of LiquidsDiffusion of Liquids
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OsmosisOsmosis
▪Diffusion of Diffusion of water across a water across a membranemembrane
▪Moves from Moves from HIGH water HIGH water concentration concentration (low solute) to (low solute) to LOW water LOW water concentration concentration (high solute)(high solute)
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Diffusion across a membrane
Semipermeable
membrane
Diffusion of HDiffusion of H22O Across A O Across A MembraneMembrane
▪High water potential = low solute concentration▪Low water potential = low solute concentration
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3 Types of solutions
▪Isotonic▪Hypotonic▪Hypertonic
▪THINK IN TERMS OF SOLUTE CONCENTRATION NOT WATER CONCENTRATION!!!!
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Cell in Isotonic SolutionCell in Isotonic Solution
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CELLCELL
10% NaCL90% H2O
10% NaCL
90% H2O
The cell is at _______________.equilibrium
ENVIRONMENTENVIRONMENT
NO NET NO NET MOVEMENMOVEMENTT
Cell in Hypotonic SolutionCell in Hypotonic Solution
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CELLCELL
10% NaCL90% H2O
20% NaCL
80% H2O
What is the direction of water movement?
Cell in Hypertonic Cell in Hypertonic SolutionSolution
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CELLCELL
15% NaCL85% H2O
5% NaCL95% H2O
What is the direction of water movement?
ENVIRONMENTENVIRONMENT
Ways to Remember Solutions
▪ “SALT SUCKS”▪ Water wants to join the party
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Think about it:
▪ Why do you cook onions before you salt them?
▪Why did pioneers use salt to cure their meats (remember no refrigerators)
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Cytolysis & Cytolysis & PlasmolysisPlasmolysis
▪Cytolysis – Cells swell and burst
▪Plasmolysis – Cells shrink and shrivel
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Osmosis in Red Blood CellsOsmosis in Red Blood Cells
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IsotonicIsotonic Hypotonic
Hypertonic
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hypotonic hypertonic isotonic
hypertonic isotonic hypotonic
Facilitated DiffusionFacilitated Diffusion
▪Doesn’t require energy
▪Uses transport proteins to move material from a high to low concentration▪Examples: Glucose or Examples: Glucose or amino acids moving from amino acids moving from blood into a cell.blood into a cell.
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Proteins Are Critical to Proteins Are Critical to Membrane FunctionMembrane Function
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Types of Transport ProteinsTypes of Transport Proteins
▪Channel proteins are embedded in the cell membrane & have a pore for materials to cross ▪Carrier proteins can change shape to move material from one side of the membrane to the other
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Channel Proteins
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Carrier ProteinsCarrier Proteins
▪Carrier Carrier proteins proteins change shape change shape to move to move materials materials across the across the cell cell membranemembrane
Active TransportActive Transport
▪Requires energy or ATP
▪Moves materials from LOW to HIGH concentration
▪AGAINST concentration gradient
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Active transport ExampleActive transport Example
▪Sodium/ Potassium pump▪Pumping Na+ (sodium ions) out and K+ (potassium ions) in against strong concentration gradients.
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Sodium-Potassium Sodium-Potassium PumpPump
Types of Active Transport
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Exocytosis
▪Molecules moved out of the cell
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ExocytosisExocytosisExocytic Exocytic vesicle vesicle immediately immediately after fusion after fusion with plasma with plasma membrane.membrane.
Endocytosis
▪Molecules moved into of the cell▪2 types
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Pinocytosis
▪Most common form▪Moves dissolved molecules into cell▪Cell “drinking”
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Example of Example of PinocytosisPinocytosispinocytic vesicles forming mature transport vesicle
Transport across a capillary cell (blue).
Phagocytosis
▪Used to engulf large molecules to bring into cell▪Cell “eating”
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Phagocytosis About to OccurPhagocytosis About to Occur
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PhagocytoPhagocytosissis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue)