Membrane Transport Lecture 21 Chapter 12 If one

Membrane Transport Lecture 21 Chapter 12

If one makes a pure lipid membrane; 1) It would be biologically inert 2) Many molecules could not transverse to the other side If one add the right proteins to it; 1) It would be biologically active 2) Many molecules could transverse to the other side 12_01_transport_prot. jpg

Can I get through please? 12_02_diffusion_rate. jpg Depends… Who are you? How big are you? Are you charged? YES NO NO

If I cannot get diffuse across, can you help? 12_03_carrier_channel. jpg YES - but only if you fit through the right protein turnstile! 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 1) not just with ATP - which is the most utilized 2) Also by coupling to another solute with concentration gradient 3) 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 _____? 12_16_osmosis. jpg Too much pressure and the membrane will rupture!

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

A nerve impulse uses channel proteins and lots of them. . 12_30_neuron. jpg

12_33_3_conformations. jpg

12_34_Ion_flows. jpg

12_38_act_potential_propg_p art 2. jpg

12_40_nerve_terminal. jpg

12_41_ion_channel_synp. jpg

12_43_excitatory_inhib. jpg