Ch. 12 Transport Across Cell Membranes pt. 2

Discuss how acetylcholine (Ach) binding to Ach receptors is an example of a ligand gated channelAcetylcholine (Ach) binds to the Ach receptor on the channel, which causes the channel to open, allowing Na to move through the channel (Acetylcholine is the ligand that binds to the channel, opening it, and allowing Na to move through it)Discuss how a voltage gated ion channel and a ligand gated ion channel work together in stimulating muscle contractionIn most cells, the cytoplasmic concentration of Ca is low. At the end of the nerve cell of the axon, there is a voltage gated calcium channel, that when opened Ca will tend to move into the cell and down its concentration gradient. When increasing cytosolic concentration of Ca, this causes vesicles to fuse with the plasma membrane, releasing acetylcholine into the space between the neuron and the muscle cell. Acetylcholine is then a ligand for a ligand gated channel on the muscle cell, binding to the channel and allowing Na to move into the muscle cell.Where can you find porins?porins can be found in the membranes of.... 1. nuclei 2. mitochondria 3. chloroplasts 4. some bacteriaWhich are more specific: ion channels or porins?Ion channels are more specific Porins are larger and less specific than ion channelsT or F Porins are larger and less specific than ion channelstrueSome porins are non-specific and are found in ............. The porins will help regulate osmotic pressuregram-negative bacteriaDo porins have selectivity filters?No, they do not.Porins tend to let things pass based on..sizeWhat do the porins located on gram-negative bacteria do?they help to regulate osmotic pressure, allowing various molecules in and various molecules out - water tends to move where solutes are higher in concentration, so as osmotic pressure changes the porins allow things to move in or out so that water may follow.T or F Some porins allow antibodies to move through a membrane, other allow nutrients, etctrueA special type of porin that allows water to pass through a membraneaquaporinA nucleoporin can ONLY be found where?in the nuclear envelope of eukaryotic cellslarge complexes of proteins that extend through both layers of the nuclear envelope of eukaryotic cellsnucleoporinWhat would nucleoporins be used for?to move enzymes that replicate DNA or enzymes that are involved in transcription inside the nuclear envelope. Once mRNA/other RNA are made, they must pass through the nucleoporin into the cell cytosolAre nucleoporins specific?not very, they allow a lot of different enzymes and proteins to move into the nucleus and various types of RNA out of the nucleusUsually things moving through nucleoporins are transported by some ________ that will interact with the pore of the nucleoporinproteinThe proteins that move solutes by passive transport OR by active transport can be classified as.....1. uniporters 2. symporters 3. antiportersTransporters that carry a single solute across the membraneuniporterTransporters that move multiple solutes in the same directionsymporterTransporters that move multiple solutes in opposite directionsantiporterTransporters that move multiple solutescoupled transportersIn passive transport involving transporters, a solute is always moved....down its chemical or electrochemical gradientAre transporters involved in passive transport specific?yes for example - the transporter that moves amino acids wont move glucoseAlmost all transporters involved in passive transport work according to what model?alternating conformation model - meaning the protein changes shape to allow things to move from one side of the membrane to the otherGluT transporters are a family of proteins for the _____________ of glucosepassive transportWhat type of transporter are the GluT transporters?uniporter - a glucose is moved into the glucose transporter and binds to the glucose-binding site, opening the transporter and moving the glucose into the cytosolActive transport involves proteins called...pumpsIn active transport, solutes are moved...against their chemical or electrochemical gradientuse the energy of ATP to move solutes AGAINST their gradientsATP driven pumpsThe _________ works to maintain non-equilibrium concentrations of Na and K across plasma membranesNa/K pumpWhat are the 2 types of ATP driven pumps we examined in class?1. Na/K pump 2. H ion pumpThe Na/K pump is a(n) _________ that is ATP drivenantiporter (Na is moved out and K is moved in)The Na/K pump uses _______ as an energy source to move Na from where its low to where its high, and to move K from where its low to where its highATPWhen referring to cells and Na/K pumps, Na is very high in concentration (inside or outside the cell?), and is very low (inside or outside?)Na is very high in concentration outside of the cell, and very low insideWhen referring to cells and Na/K pumps, K is very high in concentration (inside or outside the cell?) and low (inside or outside?)K is low outside of the cell and high insideAn ATP driven H pump is a ............ in lysosome membranesuniporterH pumps are ATP driven uniporters located on the membrane of.....lysosomesWhat must happen for lysosomal enzymes to become activated?lysosomal enzymes are activated when the H ion pump moves hydrogen ions from where they are low in concentration to where they are high in concentration (against its concentration gradient)For every _____ Na that are pumped out of a cell by a Na/K pump, _____ K are pumped into the cell3 Na out 2 K inHow does the Na/K pump work?For every 3 Na that bind to the pump, 2 K bind. When 3 Na and 2 K bind to the pump, this triggers the pump to bind to ATP, which is hydrolyzed, providing an energy source for the pump to move Na out and K in

Ch. 12 Transport Across Cell Membranes pt. 2

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