bio notes 9.17

Many ways to cross biological membranes 1 passive

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Unformatted text preview: any ways to cross biological membranes – 1) Passive transport: no energy required- with concentration gradient (high-low) • Channel proteins facilitate diffusion – Ion channels - gramicidin – Aquaporins – Gated channels • Transport proteins facilitate diffusion larger molecules* – GLUT-1 glucose transporter – GLUT-4 insulin regulated glucose transporter 6 9/14/2013 Many ways to cross biological membranes2) Active transport: • Active transport by membrane pumps – Allows movement against a concentration gradient (active, not passive transport) – Requires ATP to drive transport – Examples: • Sodium-potassium pump • Sodium-glucose cotransporter (Gatorade, ORT) • P-glycoproteins, MDR 7 9/14/2013 ABC Transporters are one class of active transporters http://www.csc.mrc.ac.uk/d/image/ResearchImages/nLinton1.jpg 8 9/14/2013 ABC Transporters – ATP driven pumps that can mutate to cause drug resistance in bacteria, tumor cells and malaria • ABC transporters are ATP-Binding Cassette proteins that use ATP to driv...
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