Wed Febuary 7, 2007

Wed Febuary 7, 2007 - Active Transport Passive Transport...

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Henrique and Hansen 1900 Membrane fluidity can acclimate Membrane fluidity adjusted by changing the ratio of unsaturated to saturated fatty acids. Increase unsaturated fats Decrease the fluidity of the membrane. Decrease temperature Acts to decrease the fluidity of a membrane. Fusion of mouse and human cells Results in a mixing of mouse and human membrane proteins. Indicates movement of proteins in the phospholipid environment. Movement of molecules across membranes Examples Gases Steroid hormones Water Direction of movement Expect – down the concentration gradient. What about against the gradient? E.G. Sodium 5 – 15 mM in the cell; 145 mM outside. How do you move sodium out of the cell? Transport Processes Active
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o Against the concentration gradient o Requires supplied energy (ATP) o Carrier Molecule Passive o Down Concentration Gradient o Does not require supplied energy. o Diffusion (simple or facilitated)
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Unformatted text preview: Active Transport Passive Transport Processes – Simple Diffusion o Down concentration gradient o Depends on molecular movement o Does not require supplied energy o Does not use a carrier molecule Passive Transport Processes – Facilitated diffusion o Down concentration gradient o Depends on molecular movement o Does not require supplied energy When concentrations on both sides of a barrier are equal o Molecules keep moving o There is no net change in solute concentration. Semi-permeable barrier • Only some types of molecules pass through. Diffusion • Movement of molecules down concentration gradient. • From regions of high concentration to low concentration regions. Movement of Water across Membranes • From High to Low water potential. Osmosis • Diffusion of water • From higher (fewer solutes) water potential to lower water potential....
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Wed Febuary 7, 2007 - Active Transport Passive Transport...

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