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Membrane Transport. Lecture 21 Chapter 12. If one makes a pure lipid membrane; It would be biologically inert Many molecules could not transverse to the other side. If one add the right proteins to it; It would be biologically active Many molecules could transverse to the other side.
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Membrane Transport Lecture 21 Chapter 12
If one makes a pure lipid membrane; It would be biologically inert Many molecules could not transverse to the other side If one add the right proteins to it; It would be biologically active Many molecules could transverse to the other side 12_01_transport_prot.jpg
Can I get through please? Depends… Who are you? How big are you? Are you charged? 12_02_diffusion_rate.jpg YES YES NO NO
If I cannot get diffuse across, can you help? YES - but only if you fit through the right protein turnstile! 12_03_carrier_channel.jpg The carrier protein actually changes shape to allow the passage of the solute The channel protein discriminates on what is allowed through!
Does the system spend energy or not to move things? Depends on the type of transport!!! 12_04_pass_act_transport.jpg All happen freely - by diffusion - (simple or mediated) Energy needed - normally ATP
Where there's a membrane there are transporters - true for all living membranes! 12_05_carrier_proteins.jpg
A complex Ca pump - uses energy to power the pumping of JUST Ca ions from one side of the membrane to the other. 12_06_Ca_pump.jpg In this example, there is a channel inside the protein which open up
The situation can get a little more complex - here we see that the protein is acting in a slightly more complicated manner. In this example, the protein physically has to change shape each time it pumps material 12_07_conforma_change.jpg
Two forces may be at work in passive transport - if we are dealing with a charged solute across the membrane. 12_08_electroch_gradient .jpg 1) CONCENTRATION 2) MEMBRANE POTENTIAL
How many ways to power active transport - not just with ATP - which is the most utilized Also by coupling to another solute with concentration gradient Photon energy from light 12_09_active_transport.jpg
The sodium-potassium pump - very important in animal cells 12_10_Na_K_pump.jpg Its job is to keep both ions at different concentrations on either Side of the membrane
This is how it cycles - 12_12_Na_K_cyclic.jpg Remember me!
Types of carrier proteins - 3 types exist 12_13_Carrier_proteins.jpg
This is how the symport version works - all based on affinity of binding and conformational changes 12_14_symport.jpg
The same cell may employ different carrier proteins at different points to perform is tasks. 12_15_glucose_gut.jpg
Revision of Osmosis - diffusion of _________? Too much pressure and the membrane will rupture! 12_16_osmosis.jpg
Different classes of organisms use different tactics to avoid rupture… 12_17_osmotic_swelling.jpg
Animal vs Plant cells 12_18_solute_transport.jpg
Carrier proteins are highly selective due to internal shape and charge 12_19_selectivity_filter.jpg
Ion channels exist in alternative states - open and closed 12_20_ion channel.jpg
Nature has different ways to open and close these channels 12_24_Gated _ion_chan .jpg
Membrane Potential = differences in total charge 12_27_membr.potential.jpg
12_30_neuron .jpg A nerve impulse uses channel proteins and lots of them..
