Notes from 9/22-9/24
Notes from 9/22-9/24 BIOL 3301 - 002
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BIOL 3301 - 002
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This 5 page Class Notes was uploaded by Ashley Lutz on Friday September 25, 2015. The Class Notes belongs to BIOL 3301 - 002 at University of Texas at Arlington taught by Laura D Mydlarz in Summer 2015. Since its upload, it has received 40 views. For similar materials see CELL PHYSIOLOGY in Biology at University of Texas at Arlington.
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Date Created: 09/25/15
92215 TEST everything through today Lecture 7 will be on exam on Thursday Will not include Friday info if it is past Lecture 7 Quiz this weekend will be over all info from this week Channelopathies diseases caused by mutations in channel proteins Ion channels allow electric signals to occur across the membrane of the cell Ion channels are for extremely rapid movement of charged molecules into or out of the cell These charges are the source of membrane potentials Membrane potentials are created by the charge density in and out of the cell based on where our cells send those charged molecules Cell membrane permeability determines the extent to which we can hold these chemicals where we want them more permeable means less control The charge of the inside of the cell is negative compared to the charge outside of the cell Remember 2 K in for every 3 Na sent out Proteins are also a source of the negative charge in the cell In neurons potassium is relatively free to ow in and out of the cell but the electrical pull toward potassium to come inside the cell is just as strong as the force pushing potassium out of the cell to reach equilibrium concentration Equilibrium does not mean nothing is moving it means everything is moving in such a way as to maintain a given point The resting potential is the equilibrium point and is around 70mV At rest potassium channels are generally open When Sodium channels open the electrical charge ips so that the inside of the cell is and the outside of the cell is This is the exact opposite of rest for the cell Nernst potential is the same as the resting potential for a specific ion When Nernst potential is reached the NET movement of ions ceases Aka what is going in equals what is going out Sodium ions will only move out of the cell if the membrane potential is over 67ish Ion channels are proteins that are as long as the cell membrane is thick so that the ions can go all the way through the cell membrane Narrow sections of the ion channels are the portions that make sure only specific ions can move through them Nongated channels are always open nothing changes them they are there to keep an equilibrium point in the cell Gated channels open and close when we want them to gated community vs normal neighborhood K channel made of 4 subunits with a hole in the center shaped like a funnel with a narrow point that prevents K from bringing anything else with it Oxygen on R groups of amino acids bind their charge to the potassium39s charge in place of the water then spit the potassium into the vestibule which holds water that will rebind to K and pull it into the cell There are 4 Oxygens bonded to the K at a time and it is passed to the next group of 4 oxygens until it reaches the inside of the cell There are different forms of gated channels Note gated channels change shape because of something other than what it carries Pumps shapes change because of binding to what they carry Ligands change the shape of the protein they bind to but they do not move through the protein They stay inside or outside of the cell wherever they started much like ATP Voltage gated ion channel There is a set of domains that form a circle the walls of the tunnel through the membrane these are the selectivity point and they change conformations when the membrane potential changes Inactivation is basically blocking the tunnel This is done by the protein to prevent repolarization when the change in membrane potential is still sending its message to the cell Action potential is generally used regarding neurons Membrane depolarization is controlled by potassium channels and voltage gated sodium and potassium channels Polarized is the point where the cell is at its resting membrane potential Some outside signal must occur for the membrane to depolarize itself Sodium channels are the first to open This makes the cell positively charged internally The cell needs to be negatively charged Voltage gated potassium channels open to make the inside of the cell negative again Sodium channels have inactivated themselves at this point After all the gated channels are closed the sodium potassium pumps work to recreate the gradients for sodium and potassium and the normal resting potential of the membrane The entire cell will not do this at the same time It is done in segments and the depolarization runs down the cell with the depolarization at one point causing the depolarization at the next The deactivated channels keep this depolarization from owing back up the cell forcing it to move one direction only Inactivation does not last long but by the time the channels can be activated again the original depolarization has moved far enough down the cell that the voltage gated channels are not stimulated to depolarize again With ions instigating action potential positive says go negative says no Myelin is a covering of fat around the axons of the neuron This speeds the process of moving the charge across the membrane because it39s not going over the whole thing Different animals produce toxins that block ion channels or hold them open Action potential causes different chemicals to be released at the end of the cell Ligand binding channels in the dendrites of the next neuron open from binding the neurotransmitter ligands creating the action potential in the next cell Enzymes catch the neurotransmitters and push them back into the original cell 92415 Test use 4521 scantrons approximately 35 multiple choice questions 46 short answer Context We have lots of different sources of 39fuel39 We have to be able to use them all to create ATP etc Mitochondria is the organelle that converts what we consume into what we can use ATP Mitochondria could have started out as a symbiotic organism in cells They are double walled and hold their own DNA The double wall and the individual DNA are necessary for the organelle to function properly The inner membrane and the electron transport systems are the source of our cell39s ability to produce ATP ATP a nucleotide adenine sugar and three phosphates ATP is the common currency that cells can accept Any other form of energy cannot be used directly as an energy source There is potential energy contained in each molecular bond When the third phosphate is pulled off of ATP to form ADP adenosine diphosphate the energy in that bond changes from potential to kinetic energy Glycolysis Krebs cycle and Electron transport chain must all be functioning for ATP to be produced in the amounts we need it Glycolysis comes first glycoglucose lysisbreak down Glucose turns into pyruvate through this cycle net gain is extremely small only 2ATP This takes place in the cytoplasm of the cell not an organelle Krebs comes next uses the products of glycolysis to create the molecules that will be used in the mitochondria and the electron transport chain This is in the matrix of the mitochondria Realize this is a movement from outside the mitochondria to inside the mitochondria The products of the Krebs cycle must be in the matrix for the electron transport chain to function The mitochondria provide a much larger amount of ATP from the glucose than glycolysis Smaller organisms do not need mitochondria they use anaerobic respiration which produces a much smaller amount of ATP but requires less space A large organism such as us requires much more ATP and must have the mitochondria to provide it Electron transport system sends H out of the matrix and into the intermembrane space Water is produced in the matrix ATPase is an F class protein F1 is in the intermembrane space This portion is hydrophilic F0 is in the membrane hydrophobic portions to hold it in the membrane as it rotates to allow the movement of H from the intermembrane space into the matrix down it39s gradient Rotation of the F0 portion rotates the F1 portion which causes it to change conformations this is how ATP is formed Beta subunits are the portions of the F1 that bind to ADP Pi and ATP There are three conformations for the Beta subunits They always change in one order from loose to tight to open Loose will allow ADP and Pi to enter into the catalytic sites Tight position forces them to bind and open spits out the new ATP molecule Three H are needed in order for one ATP to be formed ADP has a Pi added which is called phosphorylation Oxidation is done in the electron transport system phosphorylation is done by the ATPase which is why we use the term oxidative phosphorylization ATP is produced in the mitochondrial matrix It must be moved out of the matrix in order to be used ATPADP antiporter moves both down their concentration gradients which moves ATP out and ADP into the matrix Note the diagram of where everything moves in and out of the mitochondria Mitochondria have different forms in different parts of the body based on the cell39s need for energy Based on activity different cells have more or less mitochondria and more or less cristae in those mitochondria Toxins Carbon monoxide and Cyanide block Oxygen from entering the cell and being used to clear out the electrons from the electron chain which stops the electron transport chain from moving which destroys the Proton gradient which prevents ATP formation which destroys your energy source which stops cell function which kills you
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