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The Plasma Membrane - Gateway to the Cell
4/15/2017 The Plasma Membrane - Gateway to the Cell G. Podgorski, Biol. 1010
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Photograph of a Cell Membrane
The Plasma Membrane 4/15/2017 Photograph of a Cell Membrane G. Podgorski, Biol. 1010
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Functions of Plasma Membrane
The Plasma Membrane 4/15/2017 Functions of Plasma Membrane Protective barrier Regulate transport in & out of cell (selectively permeable) Allow cell recognition Contains the cytoplasm (fluid in cell) G. Podgorski, Biol. 1010
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Structure of the Cell Membrane
The Plasma Membrane 4/15/2017 Structure of the Cell Membrane G. Podgorski, Biol. 1010
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Cell Membrane Hydrophobic molecules pass easily; hydrophilic DO NOT
The Plasma Membrane Cell Membrane 4/15/2017 The cell membrane is made of 2 layers of phospholipids called the lipid bilayer Hydrophobic molecules pass easily; hydrophilic DO NOT G. Podgorski, Biol. 1010
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The Plasma Membrane 4/15/2017 Types of Transport Across Cell Membranes Regulate transport in & out of cell (selectively permeable) G. Podgorski, Biol. 1010
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Simple Diffusion Requires NO energy
The Plasma Membrane 4/15/2017 Simple Diffusion Requires NO energy Molecules move from area of HIGH to LOW concentration G. Podgorski, Biol. 1010
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The Plasma Membrane 4/15/2017 DIFFUSION Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY G. Podgorski, Biol. 1010
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Diffusion of Liquids The Plasma Membrane 4/15/2017
G. Podgorski, Biol. 1010
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Diffusion through a Membrane
The Plasma Membrane 4/15/2017 Diffusion through a Membrane Cell membrane Solute moves DOWN concentration gradient (HIGH to LOW) G. Podgorski, Biol. 1010
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Diffusion across a membrane Semipermeable membrane
The Plasma Membrane 4/15/2017 Osmosis Diffusion across a membrane Diffusion of water across a membrane Moves from HIGH water potential (low solute) to LOW water potential (high solute) Semipermeable membrane G. Podgorski, Biol. 1010
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Diffusion of H2O Across A Membrane
The Plasma Membrane 4/15/2017 Diffusion of H2O Across A Membrane High H2O potential Low solute concentration Low H2O potential High solute concentration G. Podgorski, Biol. 1010
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Aquaporins Water Channels Protein pores used during OSMOSIS
The Plasma Membrane 4/15/2017 Aquaporins Water Channels Protein pores used during OSMOSIS WATER MOLECULES G. Podgorski, Biol. 1010
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Cell in Isotonic Solution
The Plasma Membrane 4/15/2017 Cell in Isotonic Solution 10% NaCl 90% H2O ENVIRONMENT CELL NO NET MOVEMENT 10% NaCl 90% H2O What is the direction of water movement? equilibrium The cell is at _______________. G. Podgorski, Biol. 1010
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Cell in Hypotonic Solution
The Plasma Membrane 4/15/2017 Cell in Hypotonic Solution 10% NaCl 90% H2O CELL 20% NaCl 80% H2O What is the direction of water movement? G. Podgorski, Biol. 1010
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Cell in Hypertonic Solution
The Plasma Membrane 4/15/2017 Cell in Hypertonic Solution 15% NaCl 85% H2O ENVIRONMENT CELL 5% NaCl 95% H2O What is the direction of water movement? G. Podgorski, Biol. 1010
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Cells in Solutions The Plasma Membrane 4/15/2017
G. Podgorski, Biol. 1010
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NO NET MOVEMENT OF H2O (equal amounts entering & leaving)
The Plasma Membrane 4/15/2017 Isotonic Solution Hypotonic Solution Hypertonic Solution NO NET MOVEMENT OF H2O (equal amounts entering & leaving) CYTOLYSIS PLASMOLYSIS G. Podgorski, Biol. 1010
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Cytolysis & Plasmolysis
The Plasma Membrane 4/15/2017 Cytolysis & Plasmolysis Cytolysis Plasmolysis G. Podgorski, Biol. 1010
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Osmosis in Red Blood Cells
The Plasma Membrane 4/15/2017 Osmosis in Red Blood Cells Isotonic Hypertonic Hypotonic G. Podgorski, Biol. 1010
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The Plasma Membrane 4/15/2017 G. Podgorski, Biol. 1010
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Three Forms of Transport Across the Membrane
The Plasma Membrane Three Forms of Transport Across the Membrane 4/15/2017 G. Podgorski, Biol. 1010
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Passive Transport Simple Diffusion Doesn’t require energy
The Plasma Membrane 4/15/2017 Passive Transport Simple Diffusion Doesn’t require energy Moves high to low concentration Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out. G. Podgorski, Biol. 1010
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Facilitated diffusion
The Plasma Membrane 4/15/2017 Passive Transport Facilitated diffusion Doesn’t require energy Uses transport proteins to move high to low concentration Examples: Glucose or amino acids moving from blood into a cell. G. Podgorski, Biol. 1010
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Proteins Are Critical to Membrane Function
The Plasma Membrane 4/15/2017 Proteins Are Critical to Membrane Function G. Podgorski, Biol. 1010
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Types of Transport Proteins
The Plasma Membrane 4/15/2017 Types 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 G. Podgorski, Biol. 1010
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Facilitated Diffusion
The Plasma Membrane 4/15/2017 Facilitated Diffusion Molecules will randomly move through the pores in Channel Proteins. G. Podgorski, Biol. 1010
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Facilitated Diffusion
The Plasma Membrane 4/15/2017 Facilitated Diffusion Some Carrier proteins do not extend through the membrane. They bond and drag molecules through the lipid bilayer and release them on the opposite side. G. Podgorski, Biol. 1010
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The Plasma Membrane 4/15/2017 Carrier Proteins Other carrier proteins change shape to move materials across the cell membrane G. Podgorski, Biol. 1010
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Active Transport Requires energy or ATP
The Plasma Membrane 4/15/2017 Active Transport Requires energy or ATP Moves materials from LOW to HIGH concentration AGAINST concentration gradient G. Podgorski, Biol. 1010
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The Plasma Membrane 4/15/2017 G. Podgorski, Biol. 1010
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