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Balliet SyPh Ch 4-5
NYCC Balliet System Phys Ch 4-5, Exam 1
| Question | Answer |
|---|---|
| The hydrated form of the potassium ion is considerably smaller than the hydrated form of sodium because the sodium ion attracts far more _______molecules than does potassium | water |
| How does the size of potassium molecule determine its membrane selective permeability? | the smaller hydrated potassium ions pass easily through this small channel, whereas the larger hydrated sodium ions are rejected, thus providing selective permeability for a specific ion. |
| a barrier against movement of water molecules and water-soluble substances between the extracellular and intracellular fluid compartments. | lipid bilayer |
| Different proteins function differently. Some have watery spaces all the way through the molecule and allow free movement of water as well as selected ions or molecules. These are called? | channel proteins |
| bind with molecules or ions that are to be transported; conformational changes in the protein molecules then move the substances through the interstices of the protein to the other side of the membrane | carrier proteins |
| Transport through the cell membrane, either directly through the lipid bilayer or through the proteins, occurs by one of two basic processes: | diffusion or active transport |
| means random molecular movement of substances molecule by molecule, either through intermolecular spaces in the membrane or in combination with a carrier protein | diffusion |
| movement of ions or other substances across the membrane in combination with a carrier protein in such a way that the carrier protein causes the substance to move against an energy gradient, such as from low-concentration to high-concentration state. | active transport |
| What is the difference in energy requirements for diffusion vs. active transport? | diffusion just uses kinetic energy of molecules while active transport requires an extra energy source (ie, ATP) |
| continual movement of molecules among one another in liquids or in gases is called | diffusion |
| 2 types of diffusion through a cell membrane | Simple, Facilitated |
| kinetic movement of molecules or ions occurs through a membrane opening or through intermolecular spaces without any interaction with carrier proteins in the membrane. | simple diffusion |
| what determines the rate of diffusion? | number (+ amount, velocity and size of the molecules). Focus on the Number. |
| Facilitated diffusion requires interaction of a _______ protein | Carrier! |
| How does the carrier protein help the molecule get through the lipid bilayer? | binding chemically with them and shuttling them through the membrane in this form. |
| What two ways can simple diffusion occur? | Directly through the lipid bilayer for lipid-soluble molecules or through protein Channels with Water |
| One of the most important factors that determines how rapidly a substance diffuses through the lipid bilayer | lipid solubility |
| 4 molecules that have high lipid solubility and can therefore Simply Diffuse directly through the cell membrane: | Oxygen, Nitrogen, CO2, alcohol |
| the rate of diffusion of each of these substances (O+, N+, CO2, COH+) through the membrane is directly proportional to its ______________________. | lipid solubility |
| large amounts of this molecule can be delivered through the membrane as if the membrane did not exist. What is it and why? | Oxygen, because it is a gas and gases(O,N, CO2) are lipid soluble, as well as alcohol. |
| Even though water is highly insoluble in the membrane lipids, it readily passes through __________ in protein molecules that penetrate all the way through the membrane | Channels (think: water runs in channels) |
| lipid-insoluble molecules can pass through the protein pore channels in the same way as water molecules if they are ________ soluble and small enough. | water (always associate water with channels) |
| what are three characteristics of protein channels for lipid-insoluble molecules | 1) water soluble, water based 2)selectively permeable 3) many are gated |
| This results from the characteristics of the channel itself, such as its diameter, its shape, and the nature of the electrical charges and chemical bonds along its inside surfaces. | selective permeability of a protein channel |
| One of the most important selectively permeable protein channels -inner surfaces of this channel are strongly negatively charged | Sodium channel |
| Sodium is dehydrated for a selectively permeable protein channel, ergo its charge determines entrance. How does potassium gain entrance to its channels? | K+ channels are not charge-based, but size-based, because although they remain hydrated, they are much smaller than sodium and so are allowed to enter based on their size, not their charge. |
| Along with gating, size and charge are two possible ways for selectively permeable protein _______ to decide what molecules gain entrance. | size and charge |
| provides a means of controlling ion permeability of the channels. | gating of protein channels |
| 2 types of gating (in Guyton) | voltage gating and chemical (ligand) gating |
| the molecular conformation of the gate or of its chemical bonds responds to the electrical potential across the cell membrane. | Voltage gating |
| the mechanism for eliciting action potentials in nerves that are responsible for nerve signals. | voltage gating |
| protein channel gates are opened by the binding of a chemical substance with the protein | chemical/ligand gating |
| this causes a conformational or chemical bonding change in the protein molecule that opens or closes the gate | chemical/ligand gating |
| the single voltage-gated sodium channel works on what principle? | the all or none principle for opening and closing of the channel |
| At one voltage potential, the channel may remain closed all the time or almost all the time, whereas at another voltage level, it may remain open either all or most of the time. What happens at inbetween voltage? | snaps open and shut intermittently. The point is the all or none principle. |
| a substance transported in this manner diffuses through the membrane using a specific carrier protein to help. That is, the carrier facilitates diffusion of the substance to the other side. | Facilitated or carrier-mediated diffusion |
| a substance transported in this manner diffuses through the membrane using a specific carrier protein to help. | Facilitated diffusion (uses a carrier to get substance to other side through channel) |
| as the concentration of the diffusing substance increases, the rate of simple diffusion continues to increase proportionately, but in the case of facilitated diffusion, the rate of diffusion cannot rise greater than the Vmax level. Why? | The binding, conformational change, and release that a carrier protein undergoes in facilitated diffusion can only go as fast as the protein can shape-shift and return to original receiving mode. There is a limit to how fast a thing can work, ergo Vmax. |
| what determines Vmax? | In facilitated diffusion, it is the 'top speed' (conformation rate) of the carrier protein. |
| Despite having a Vmax/top speed of conformational change, why is facilitated diffusion more versatile than simple diffusion, which has no maximum rate? | Because this mechanism allows the transported molecule to move—that is, to “diffuse”—in EITHER DIRECTION through the membrane |
| 2 most important substances that cross the membrane via facilitated diffusion (and therefore have a Vmax)? | glucose, amino acids |
| _______ can increase the rate of facilitated diffusion of glucose by 10x or 20x-fold. | Insulin |
| many substances can diffuse through the cell membrane. What is usually important is the ____ rate of diffusion of a substance in the desired direction. | net |
| Affects net diffusion | concentration difference |
| rate of net diffusion into the cell is proportional to the concentration on the outside minus the concentration on the inside | Net Diffusion = Co-Ci or C(outside)/C(inside) |
| If an electrical potential is applied across the membrane, as shown in Figure 4–8B, the electrical charges of the ions cause them to move through the membrane even though... | no concentration difference exists to cause them to move along the gradient |
| You can use pressure (like a piston forcing something from one space to another), or you can use the more elegant electrical charge, attracting negative to positive and vice versa to move ions from one side to the other. All disregarding? | concentration difference |
| In nature, what two forces balance one another when moving molecules across membranes? | concentration gradient and electrical difference |
| When concentration gradient and electrical differences created a balance of univalent ions which may be determined according to what equation? | Nernst: EMF (mV)= +/-61 log C1/C2 |
| explain the variables in the Nernst eq: EMF (mV)=+/-61 log C1/C2 | EMF is electromotive force (voltage)in millivolts between side 1 (C1) and side 2 (C2)of the membrane. 61 log relates to the univalent ion of sodium Na+. |
| why is the Nernst equation determining the difference in charges between side 1 and side 2 of a membrane important to understand? | It help understand the transmission of nerve impulses in chapter 5, on which you have a test. |
| Besides concentration gradient and electrical charge, what else affects the movement of ions across a diffusible membrane? | Pressure! |
| example of a molecular place where pressure across a diffusible membrane is of great importance? | the blood capillary membrane in all tissues of the body. The pressure is about 20 mm Hg greater inside the capillary than outside. |
| the sum of all the forces of the different molecules striking a unit surface area at a given instant | Pressure! |
| When the ___________ is higher on one side of a membrane than on the other, this means that the sum of all the forces of the molecules striking the channels on that side of the membrane is greater than on the other side. | Pressure! |
| In most instances, this is caused by greater numbers of molecules striking the membrane per second on one side than on the other side | Pressure! |
| (diffusible membrane) The result is that increased amounts of energy are available to cause net movement of molecules from the _____-pressure side toward the _____-pressure side. | high, low (causing more molecules to diffuse to the low side) |
| The most abundant substance that diffuses through a cell membrane. | Water |
| normally, the amount that diffuses in the two directions is balanced so precisely that zero net movement of water occurs. Therefore, the volume of the cell remains constant. What kind of cell? | Red blood cell |
| Under certain conditions, a concentration difference for water can develop across a membrane, just as concentration differences for other substances can occur. What happens next? | A net movement of water across cell membrane causes it to swell or shrink, depending on the direction of water movement = Osmosis |
| Process of net movement of water caused by a concentration difference of water is called? | Osmosis |
| If a membrane has sodium chloride on one side and water on the other, and the water can move easily to the other side but the sodium and chloride cannot, what do we call this membrane? | selectively permeable to water, but much less so to sodium and chloride ions |
| In the instance of NaCl on one side mixed with water, and on the other side pure water, the NaCl has made a mixture of less-than pure water on its side because it cannot move across the membrane to balance the concentration of itself. Water does what? | More water molecules striking pure water side, so water will move to the side where its numbers are less, that is, it will move to the NaCl side. |
| The pressure required to stop water from moving to the NaCl side in a case of imbalance across a selectively permeable membrane is called ? | osmotic pressure (will stop water from flowing to salt) |
| Pressure can eventually oppose the osmotic effect and a balance will be struck | The pressure difference across the membrane at this point is equal to the osmotic pressure of the solution that contains the nondiffusible solute. |
| The osmotic pressure exerted by particles in a solution, whether they are molecules or ions, is determined by the __________ of particles per unit volume of fluid, not by the mass of the particles. | NUMBER (osmotic pressure likes number) |
| Why does number, not mass, determine osmotic pressure? | each particle in a solution, regardless of its mass, exerts, on average, the same amount of pressure against the membrane. Small move faster, large move slower = balance of pressure, so Number is the trump card, the deciding factor. |
| the trump card, the deciding factor determining osmotic pressure? | Number of particles |
| the factor that determines the osmotic pressure of a solution is the concentration of the solution in terms of number of particles (which is the same as its _______concentration if it is a nondissociated molecule), not in terms of mass of the solute. | molar |
| k = (mass)(velocity)/2 | mass of large particles x velocity of smaller particles divided by 2 equals their average kinetic energies (for determining osmotic pressure) |
| To express the concentration of a solution in terms of numbers of particles, the unit called the ________ is used in place of gram | osmole |
| gram molecular weight (regarding the osmole) | has to do with the number of osmotically active particles |
| simple diffusion eventually _______________________concentrations on the two sides of the membrane | equilibrates |
| When a cell membrane moves molecules or ions “uphill” against a concentration gradient (or “uphill” against an electrical or pressure gradient), the process is called | active transport |
| sodium ions, potassium ions, calcium ions, iron ions, hydrogen ions, chloride ions, iodide ions, urate ions, several different sugars, and most of the amino acids. | substances which must be ACTIVELY transported through the membrane |
| Active transport is divided into two types according to the source of the energy used to cause the transport: | primary and secondary active transport |
| uses ATP for active transport | primary active transport |
| energy is derived directly from breakdown of adenosine triphosphate (ATP) or of some other high-energy phosphate compound. | primary active transport |
| Active transport is divided into two types according to the source of the energy used to cause the transport: | primary and secondary active transport |
| uses ATP for active transport | primary active transport |
| energy is derived directly from breakdown of adenosine triphosphate (ATP) or of some other high-energy phosphate compound. | primary active transport |
| the energy is derived secondarily from energy that has been stored in the form of ionic concentration differences of secondary molecular or ionic substances between the two sides of a cell membrane, created originally by primary active transport. | secondary active transport |
| In both primary and secondary active transport, both depend on? | carrier proteins that penetrate through the cell membrane, as is true for facilitated diffusion |
| How is the carrier protein in active transport different from that of one in facilitated diffusion? | in AT, the carrier protein has to impart some energy to the transported substance to move it across the electrical or chemical gradient |
| The sodium-potassium pump is an example of what kind of transport? | primary active transport |
| sodium, potassium, calcium, hydrogen, chloride are transported how? | primary active transport |
| The active transport mechanism that has been studied in greatest detail is the | Sodium-Potassium Pump (Na/K pump) |
| a transport process that pumps sodium ions outward through the cell membrane of all cells and at the same time pumps potassium ions from the outside to the inside | Na-K pump (primary active transport) |
| one of its 3 jobs is to establish a negative electrical voltage within the cell. | Na-K pump (primary active transport) |
| one of its 3 jobs is the transmission of nerve signals throughout the nervous system, and is therefore the basis of nerve function. | Na-K pump (primary active transport) |
| name the 3 jobs of the Na-K pump: | 1-maintain the Na and K differences across the cell membrane, 2-create a negative internal charge for the cell, 3-transmission of nerve signals throughout nervous system |
| What constitutes the carrier protein of the Na-K pump for primary active transport? | large Alpha subunit and smaller Beta subunit |
| describe the large Alpha subunit of the Na-K pump | has 3 binding sites for Na+ on the inside-face and ATPase active sites on the inside-face, while having 2 binding sites for K+ on the outside-face. Thus the ratio: 3Na out for every 2K in |
| what causes the conformational change in the Na-K pump? | The splitting of the ATP, releasing a high-E phosphate, when the 2 potassium slots fill on the outside-face and the 3 sodium slots fill on the inside-face of the protein. Boom! Shift and Swap! |
| What is cool about the Na-K/ATPase pump for primary active transport? | It can run in reverse if the concentrations shift |
| what does 'run in reverse' mean for the Na-K/ATPase pump? | synthesize ATP from ADP and a Phosphate ion, throw out potassium (2) and bring in sodium (3) |
| One of the most important functions of the Na+-K+ pump is to control the __________ of each cell. | volume |
| Without function of this pump, most cells of the body would swell until they burst | Na-K/ATPase pump |
| Inside the cell are large numbers of proteins and other organic molecules that cannot escape from the cell. Most of these are negatively charged and therefore attract large numbers of potassium, sodium, and other positive ions as well. What happens? | Causes osmosis of water into the cell (following the particles like it follows salt). If the Na-K/ATPase pump didn't equalize the volume by pumping out sodium, the cell would burst! |
| Why doesn't sodium Na+ try to get back into the cell once the Na-K/ATPase pump kicks it out? | the membrane is far less permeable to sodium ions than to potassium ions, so that once the sodium ions are on the outside, they have a strong tendency to stay there |
| If a cell begins to swell for any reason, this automatically activates the ___________ moving still more ions to the exterior and carrying water with them. | Na-K/ATPase pump for primary active transport |
| performs a continual surveillance role in maintaining normal cell volume | Na-K/ATPase pump |
| the Na+-K+ pump is said to be __________ because it creates an electrical potential across the cell membrane | Electrogenic (every time it kicks an Na+ out, it makes the inside more negative, so it has the ability to generate the charge on the membrane = electrogenic) |
| Like the Na-K/ATPase pump, the Calcium pumps are another kind of | primary active transport pump |
| Calcium ions are normally maintained at extremely ______ concentration in the intracellular cytosol of virtually all cells in the body | low |
| what keeps Calcium at extremely low levels within the cell? | the Calcium pumps! |
| Why do we refer to Calcium pumps instead of pump? | One in cell membrane pumps calcium to the outside of the cell. The other pumps calcium ions into one or more of the intracellular vesicular organelles of the cell, such as the sarcoplasmic reticulum of muscle cells and the mitochondria in all cells |
| How many calcium pumps are there in each cell? | 2! One pumps Ca+ out altogether and the other one pumps it into organelles like mitochondria |
| The Na-K pump and Ca+ pump are alike because both use? They are different because? | ATP, the cell requires 2 Ca+ pumps |
| Primary active transport of H+ is very important in the body in 2 places: | stomach (hydrochoric acid), and the distal tubules/collecting ducts of kidneys |
| (1) in the gastric glands of the stomach, and (2) in the late distal tubules and cortical collecting ducts of the kidneys. | where Hydrogen pump primary active transport is very important |
| In the gastric glands, the deep-lying __________ cells have the most potent primary active mechanism for transporting hydrogen ions of any part of the body. | parietal |
| the basis for secreting hydrochloric acid in the stomach digestive secretions | H+ pumps in the parietal cells of the the gastric glands of the stomach |
| At the secretory ends of the gastric gland parietal cells, the hydrogen ion concentration is increased as much as a millionfold and then released into the stomach along with chloride ions to form? | Hydrochloric acid |
| large amounts of hydrogen ions are secreted from the blood into the urine for the purpose of eliminating excess hydrogen ions from the body. What does this? fluids. | intercalated cells in the distal tubules & collecting ducts of the kidneys |
| The amount of energy required to transport a substance actively through a membrane is determined by how much the substance is ________________ during transport. | concentrated |
| Compared with the energy required to concentrate a substance 10-fold, to concentrate it 100-fold requires ________ as much energy, and to concentrate it 1000-fold requires _______ times as much energy. | twice, three |
| the energy required is proportional to the logarithm of the degree that the substance is concentrated, meaning? | It requires a base-10 log to calculated the energy required to concentrate a substance more and more, ie 10x is once, 100x is twice as much energy, 1000x concentrated is three times as much energy required |
| Energy in calories per osmole= (1400 log)(C1/C2) | this shows us how much energy the cell has to spend to concentrate a substance, using the idea that 100x more concentrated takes twice as much energy as 10x concentrated, etc. |
| If the amt of energy it takes to convert 1 osmole of substance 10x is 1400 calories, then what is the amt calories required to convert it to a 100x more concentrated form? | 2800 calories, because 10x=1400 and we know 100x is twice as much energy so (2)(1400)=2800 calories |
| Some cells, such as those lining the renal tubules and many glandular cells, expend as much as 90 per cent of their energy for this purpose alone | concentrating substances |
| Na, Ca, Cl, Bicarb, glucose are inside or outside the cell? | outside |
| K, Mg, Phosphate, Sulfate, amino acids are inside or outside the cell? | inside |
| The only way sodium can move is | in (if talking diffusion/pore alone) |
| Ions require a _________________ to move across the barrier | channel protein |
| 3 kinds of diffusion | simple, facilitated, osmosis |
| primary active transport is _____-bound. | ATP |
| secondary active transport uses the | Na/K-ATPase pump |
| how do water-soluble components cross the cell membrane? | proteins in the membrane |
| secondary active transport uses the Na/K-ATPase pump. There are 2 kinds of proteins: | symport (co-transport as in "sym" like together) and anti-port (counter-transport as in swap) |
| S.F.O. cannot break diffusion rules, meaning Na can only move ____, K can only move ____, and Ca can only move _____ | Na in, K out, Ca in |
| diffusion depends on having more ____________ | surface area |
| examples that increase surface area for diffusion | alveoli, microvilli |
| diffusion requires a good ________ ___________, meaning when there is a lot outside the cell, there is wonderful diffusion! | concentration gradient |
| when you change the concentration gradient on a tightly regulated ion like Ca++, dropping the level causes | ineffective nerve transmission |
| Diffusion depends on the ______ of openings/transporters and the ______ of the openings! | number and size, baby! |
| diffusion depends on: (3) | surface area, conc. gradient, number and size of openings |
| type of diffusion with no carrier protein | simple diffusion |
| type of diffusion requiring a carrier protein | facilitated |
| what happens to facilitated proteins of a rate:solute graph? | facilitated plateau out because the rate can only go as fast as the protein can shape shift and swap out the molecules |
| small lipid soluble molecules move through the ___________ of the lipid bilayer. | interstices |
| examples of small lipid soluble molecules that move through the interstices of the lipid bilayer (4) | Oxygen, CO2, alcohol, Nitrogen |
| small water soluble molecules move through watery channels that penetrate all the way through some large _________ proteins. | transport |
| examples of small water soluble molecules that move through watery channels are (2) | water, ions |
| movement through protein channels can be described as movement through a | selectively permeable ion channel |
| Selectively permeable ion channels are opened or closed by | gates |
| how are the gates of selectively permeable ion protein channels controlled? | ligand or voltage |
| there is a flux of ions through channels without _________ expenditure | energy |
| what influences the rate but not the direction of ion flux | membrane potential |
| membrane potential influences the _____ but not the direction of ion flux | rate |
| how were transmembrane alpha helix proteins discovered? | with artificial ionophores |
| ionophores, used to discover transmembrane alpha helix proteins, are? | artificial |
| transmembrane alpha helix proteins exist in ___ or more configurations | 2 |
| transmembrane alpha helix proteins are stable whether they are open or closed. Where are they? | nerve cells! |
| nerve cells have what kind of ion channels? | transmembrane alpha helix proteins |
| facilitated diffusion uses _________ protein | carrier |
| carrier-mediated diffusion is another term for | facilitated diffusion |
| In facilitated diffusion, the carrier protein acts like an | enzyme |
| In facilitated diffusion, the rate of diffusion reaches Vmax. In other words, it | plateaus because the maximum Velocity is only as fast at the protein can swap ions |
| Examples of the facilitated diffusion mechanism (2) | amino acids and glucose |
| what uses facilitated diffusion? | amino acids and glucose |
| best studied facilitated diffusion mechanism? | glucose transporter |
| describe the glucose transporter: | best studied, multipass (7-pass) transmembrane protein |
| what are the 2 Insulin INdependent glucose transporters? | Glut 1 and Glut 2 |
| describe Glut 1 transporter | Insulin INdependent, multipass transmembrane, Brain and RBC |
| describe Glut 2 transporter | Insulin INdependent, multipass transmembrane, LIVER |
| what is different about Glut 2 transporter from all other three? | It's the only one that lets glucose in AND out because it is the liver and the liver can actually make glucose. Everybody else only lets glucose in because nobody else can make it. |
| Liver uses which glucose transporter? | Glut 2 |
| why does it make sense for the brain and RBC (glut 1) and the liver (glut 2) to be insulin INdependent transporters? | because the brain doesn't care, the RBC's have to have glucose and the liver can make its own. These are all independent, I-don't-give-a-crap-what-you-want states. |
| the one insulin dependent glucose transporter | Glut 4! Dependent on insulin door! Muscle and fat can't have any more! |
| Net diffusion is the proportion of Concentration _____ to Concentration ______ | inside, outside |
| EMF in mV = -61 log (Cinside/Coutside) | Concentration inside divided by Concentration outside to give net diffusion using -61 log. If negative ion like Cl-, change -61 to +61. |
| If I have a charge, I can move ________ the concentration gradient. | against |
| If I have a charge, I can move against the concentration gradient and change the | membrane potential. |
| The __________________ causes ions to move toward the opposite charge AGAINST the concentration gradient. | membrane potential |
| The membrane potential is causing ions to move towards the opposite charge against the concentration gradient, while __________ causes the ions to move WITH the gradient. | diffusion |
| Membrane potential (against c.g.) vs. Diffusion (with c.g.) = homeostasis is determined by the __________ equation | Nernst |
| The Nernst equation determines homeostasis of __________ ions like Sodium | univalent |
| Molecules will always move from an area of high concentration to an area of low concentration (excepting the membrane opposite charge pull), so what does pressure difference have to do with diffusion? | molecules move from areas of high pressure to area of low pressure. Higher pressure = lower volume |
| higher pressure corresponds with lower | volume |
| what variable doesn't give a damn about concentration and pressure gradients if there are particles (solute) laying about? | water! Likes to dilute so follows particles/solute wherever, in or out, regardless of pressure or conc. gradient |
| most abundant molecule that diffuses across the membrane | water |
| normally the _____ movement of water is zero. | NET |
| the NET movement of water is normally? | zero |
| the process of net movement of water is called | osmosis |
| flow of water across a membrane from lower to higher solute (particle) concentration | osmosis |
| how does water move so freely across lipid bilayers? | through membrane pores (water protein channels) |
| the amount of force applied to prevent water from moving across the membrane (escaping or entering to follow those rock star solutes!) is called? | osmotic pressure |
Created by:
hecutler