BIO 110, Ch. 5 Notes Part 2
BIO 110, Ch. 5 Notes Part 2 BIOL 110
University of Louisiana at Lafayette
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This 4 page Class Notes was uploaded by Kaylen Harrison on Friday September 23, 2016. The Class Notes belongs to BIOL 110 at University of Louisiana at Lafayette taught by Patricia L. Mire-Watson in Fall 2016. Since its upload, it has received 8 views.
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Date Created: 09/23/16
CH. 5 Notes Part 2 Kaylen Harrison • Transporters a.k.a carries (not channels ) --Fig 5.19 § Difference btw channels and transporters • There's no gating • They don’t go straight through an open passageway, they bind to the proteins at a particular place and are unbinding (turning it loose) to get to the other side • Involved in carrying, physically grabbing hold of the solute and moving it • Uptake of organic molecules • Key role in export • Channel doesn’t bind, just m akes a passageway • Transporter carry's it and moves it to the other side of the membrane • Binding site in transporter • Where the solute binds • When solute binds, protein changes it shape (conformation) • It changes it conformation to make the pockets move to t he opposite side of the membrane • From there, the solute can diffuse away • Cells use these types of transporters for taking up organic molecules such as glucose • Use transporters for exporting things out of the cell • Proteins can allow substances to go in either direction. • Into the cell or out of the cell ' • 3 flavors of transporters • Flavored according to how many substances they move and relative direction of those substance s • Uniporter • One molecule or ion being moved by transporter • Symporter (Co transporter) • Two or more ions or molecules being transported in the same physical direction • Antiporter (opposite) • Two or more ions or molecules being transported in opposite physical directions • These all can be used for either passive or active transport • Active Transport o Energetically unfavorable and requires input of energy • Cell has to use energy to move these substances § Movement of the solute from low concentration to high concentration (against gradient) o In some cases, the transport protein uses ATP directly as a source of energy to transport the solute-----Primary Active transport • Looking for ATP for primary active transport o Using concentration gradient of another substance to move a different substance against its concentration ---secondary active transport • Fig. 5.22a---primary active transporter b/c see ATP § Moving hydrogen ions, binding to the binding site and changing its confirmation to release these hydrogen ions on this side of the membrane § Hydrogen ions moving against the concentration gradient • Can’t use diffusion to do this § Uniporter b/c only moving hydrogen ions § 2nd transporter • Transporting 2 substances • Bring transported in the same direction so a symporter • Anytime even one of the substanc es are being moved against its concentration gradient, it’s going to be Active transport • There's no ATP, so its secondary • Energy comes from the triangle moving down their concentration gradient • This transport protein is coupling • Coupling an energetical ly favorable thing (downward movement of the triangle) to an energetically unfavorable thing (movement of the balls up their concentration gradient --against) • If triangles release enough energy as they're moving down their concentration gradient, then that energy can be used to move the ball up its concentration gradient • Both moving in same physical direction • Moving according to a concentration gradient is one thing • Moving in the physical direction is something different • Symport b/c being moved in same physical direction • What happens if this protein stops working and runs out of ATP? • So this protein will stop working and will affect the ability of the other protein to stop working. • Eventually going to get the same concen tration on both sides • Once the proton concentration is lost, the protein won’t be able to do its thing anymore • Secondary active transporters depend on primary active transporters to establish and maintain the gradient that they are going to use • They don’t use ATP directly but indirectly, if the cell loses energy, they will eventually stop working too. o Sodium potassium ATPA. Also known as sodium potassium ____. • Sodium and potassium are both being transported, so wither sym or antiporter depending on the physical directions that they are moving. § 3 Na's (sodium’s) are being exported while 2 potassium's (k) are being imported. So this is the opposite direction. So antiporter § Its primary b/c its ATP driven ions § Using energy from ATP hydrolysis for it to wo rk § Exports 3 positives for every 2 positives it brings in • Throws out 3 and lets in 2 • So every time it works, the cell is losing a net of 1 positive • This pump is extremely important for neurons b /c neurons rely on that charge difference across an membra ne to make electrocitity • b/c it establishes a charge gradient (a charge difference) it ’s called electrogenic • Its generating a charge difference • There's a place for sodium to bind and they bind to get transported 3 of those out of the cell and in potassium , 2 of those will bind and get transported into the cell • Each of the ions that are being transported as being transported against their concentration gradients • Sodium is going out and there's already high sodium out, so that goes against the concentration gradient • Potassium is being brought in and there's already high potassium in it, so that goes against the concentration gradient too • So could the cell use act ive transport to transport these two ions if it wanted to? • Remember, with secondary an ion has to be transported with is gradient and the other against • So NO, b/c they're both being transported against the concentration o Diffusion is driving the proteins to go through a channel o Channels are always passive transports • Exocytosis & Endocytosis o When cells want to transport a lot of something at once or large particles such as proteins, molecules, disaccharides, etc., they can transport these kinds of things by either exo or endocytosis. These particles can either move in or out • Exocytosis § Things are going to be exiting • Endo § Coming in • The cell does this by packaging these materials into vesicles (bubble shaped organelles in the cell) and they move the vesicles to where they need to go • If Endocytosis, materials gets packaged into the vesicle by the membrane by invaginating • Ig exocytosis, vesicle fuse with the plasma membrane § 3 types of endo • cell eating --phagocytosis • Cell drinking --pinocytosis • Receptor-mediated endocytosis o Fig • A vesicle budding off of the Golgi (packing/shipping center of the cell) • Packaging something that it needs to ship out of the cell • Cage around the vesicle is a coat of proteins that are needed to get the vesicles to be transported • Vesicle is moved all the way to the plasma membrane, coat sheds and the lipids of the vesicle are going to fuse with the lipids of the plasma membrane • Membranes can fuse and bud off of each other • Two membranes fuse and vesicle comes a part of the plasma membrane and in doing so it spits out what was inside ---exocytosis • Endocytosis § Collect some cargo from the environment (extracellular space) by forming a pocket in the membrane =invagination (membrane forming a pocket) § When it has enough car go it pinches off of the membrane as a vesicle, the coat surrounds it, and the vesicle is brought to wherever it needs to go in the cell § In many cases, this involves vesicle fusing with the lysosome and the lysosome digest it. • Lysosomes have acid hydrolases. They hydrolyze it § This one is receptor mediated b /c it involves some proteins that are binding the part that needs to be transported. § These proteins are very specific and will only bind to particular substances. § This allows the cell to take in substances that it wants and not just anything. § So cargo has to bind to the receptor first and then the rest of the _____ happens.
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