Chapter 7 Membrane Structure & Function

Slide 2 of Plasma Membrane  Cell’s ______ to the external world  Selectively permeable  Allows ____ ________ _______ through  Most molecules _______ ____ into the cell  Small hydrophobic molecules _____ _____ __ ____  ____ and ____

Slide 3 of 38 Plasma Membrane (Page 2)  Main constituents: ___________ & ________  Membrane _______  Allow ________ _______ into the cell  Phospholipid bilayer  ______ to most things  __________  ________ & ________ regions  ________ head & ________ tail

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Slide 5 of 38 Fluid Mosaic Model

Slide 6 of 38 Fluid Mosaic Model  Mosaic due to _______ _________  Fluid due to the _____________ _______  Unsaturated hydrocarbons = ______ _______  Higher Temperature = ______ _______  Cholesterol = ___________ _______  _______ fluidity at ____ temps.  _______ fluidity at _____ temps.

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Slide 8 of 38 How does it get in?  Phospholipid bilayer is the __________ ________  Only _____ & ________ can cross  _________ molecules are unable to enter  Water & other polar molecules = __ _______  For most molecules (_____ ______ _____) ___________ _________ allow passage  _______ _______ – Bound to 1 surface of the membrane  _______ _______ – embedded in membrane  ___________ ________ – completely span the membrane

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Slide 12 of 38 Membrane Proteins  _______ proteins  ________ proteins  ________ _______  Cell-to-cell OR Cell-to-ECM adhesion  _______ proteins  Type of ____________ ______  Transport ___________ ________ across membrane  ____________  Transport protein for _______ _____ _____ _________

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Slide 16 of 38 Membrane Carbohydrates  Function in ________ ____________  Cell’s ability to __________ ____ ______  Basis for _______ of foreign cells by the immune system  ______ ______ result from membrane carbohydrates

Slide 17 of 38 Questions 1. What do small & nonpolar substances require to cross the membrane? 2. What is an amphipathic molecule? 3. Explain why it is called the “fluid mosaic” model of the membrane? 4. What is the function of membrane proteins? 5. What is the function of a membrane carbohydrate? 6. What does adding cholesterol do to alter a membrane?

Slide 18 of 38 Passive Transport  Diffusion – movement from an area of ____ concentration to an area of ____ concentration  Moving down a __________ _______  __ energy expenditure for this transport  Osmosis – diffusion of _____ across a _________ ___________ _________  Osmosis is only ____ __ _____ (for us)  Requires a _________ _________

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Slide 20 of 38 Tonicity

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Slide 22 of 38 Facilitated Diffusion  Transport proteins that allow ____________________ to cross the membrane  _______ transport but requires a ________ ______  Two means of operation  1. ______ Proteins - ________ ________  2. ______ Proteins – shape change = __________

Slide 23 of 38 Facilitated Diffusion (Channel Protein)

Slide 24 of 38 Facilitated Diffusion (Carrier Protein)

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Slide 26 of 38 Questions? 1. How is facilitated diffusion different from simple diffusion? 2. What type of energy does facilitated diffusion require? 3. What are the 2 versions of facilitated diffusion? 4. How is osmosis different from diffusion? 5. What is a concentration gradient? 6. Passive transport goes down or goes against the concentration gradient?

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Slide 28 of 38 Active Transportation  Some transport proteins do facilitated diffusion, other do active transport  Active transport = ______ proteins only  why?  Move substances _______ their concentration gradient  _______ concentration  _______ concentration  Requires _____ __ ____  Maintains _______ & ______ internal environment  _________ or _______ a gradient

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Slide 30 of 38 Na+/K+ Pump  Watch Na+ / K+ Animation

Slide 31 of 38 Electrochemical Gradients  Not concentration gradient, but electrochemical gradient  Both ___________ & ______ gradients  Commonly referred to as _________ ________  Negative = ______  Favored movement:  Anions  ____  Cations  ___

Slide 32 of 38 Electrochemical Gradients  Ions move down their concentration & ionic gradients  Transport protein that establishes a voltage across the membrane = ___________ _____  Na+/K+ Pump  Proton Pump

Slide 33 of 38 CoTransport (Secondary Active Transport)  Electrogenic pump creates a concentration gradient  THEN Ions move down their gradient, and ACTIVELY transport another substance

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Slide 35 of 38 Movement of LARGE molecules

Slide 36 of 38 Animation swf

Slide 37 of 38 Phagocytosis & Pinocytosis  Phagocytosis – cell membrane wraps around and takes in a ____ ________  Form of ________  Called “cell eating”  Pinocytosis – cell membrane wraps around and takes in ______ _______ __ ______ (extracellular fluid)  Form of __________  Called “cell drinking”

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