Physiology Lab Experiment 1 – Flashcards
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In _____ process, the cell must provide energy in the form of ATP to power the processes
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Active Transport
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Define Diffusion:
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the movement of particles from an area of greater concentration to an area of lesser concentration
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Active Transport:
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ATP is used to power
Solutes are moving against their gradient
Uses a membrane-bound carrier protein
Can only occur in certain animals
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The dialysis tubing will mimic the ___ _____ if the cell
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Plasma Membrane
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The larger the _____ ______ of a compound, the larger the pore size required for passive transport of that compound
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Molecular weight
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Plasma membrane is selectively permeable meaning
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Allows nutrients and appropriate amounts of ions to enter the cell
Keeps out undesirable substances
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Passive Processes:
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Transport process is driven by concentration or pressure differences (gradients) between interior and exterior of the cell
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Two forms of diffusion
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Simple and facilitated
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Simple diffusion
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occurs without membrane proteins
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Facilitated Diffusion
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requires a membrane-bound carrier proteins that assists in the transport
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In both simple and facilitated substance moves____or ___ the concentration gradient of the solute, energy in the form of ____ _____ comes from the constant motion of the molecules
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with or down
kinetic energy
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osmosis
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water moves with its concentration gradient, from a higher concentration of water to a lower concentration of water
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Filtration:
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Usually occurs only across capillary walls
Depends upon a pressure gradient as it is driving force
Not a selective process
Dependent upon the size of the pores in the filter
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Active Processes
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cell provides ATP to power the transport
solutes move against their concentration gradient
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Vesicular transport includes
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phagocytosis, endocytosis, pinocytosis and exocytosis
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The driving force for diffusion is
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the kinetic energy of molecules in motion
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In diffusion, molecules move from
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high concentration to low concentration
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The higher the MWCO number,
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the larger the pore size
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Avogadro's number is
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a constant for the number of molecules
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All molecules possess kinetic energy and
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are in constant motion
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Concentration Gradient:
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differences in concentration
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Diffusion occurs when
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The net effect of random molecular movement is that the molecules eventually become evenly distributed throughout the environment
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Will urea with a molecular weight of 60.07 diffuse through the 20 MWCO membrane?
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no
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The reason sodium chloride didn't diffuse left to right is that
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The membrane pore size was too small
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The rate of diffusion for urea
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Is slower than that for sodium because urea is a larger molecule
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Did any solutes move through the 20 MWCO membrane? Why or why not?
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No, all of the molecular weights were too large
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Did NaCl move through the 50 MWCO membrane
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Yes
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Describe how the size of a molecule (molecular weight) affects its rate of diffusion.
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The smaller, the faster the diffusion
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What happened to the rate of diffusion when you increased the NaCl solute concentration?
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Diffusion increased
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The effect of increasing the concentration of sodium chloride from 9 mM to 18 mM in the left beaker was to
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Increase the rate of diffusion
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Describe the difference between the rate of diffusion seen for sodium and urea.
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Urea diffused more slowly because it is larger than sodium
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What of the following solutes did not pass through any of the membranes
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Albumin
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When diffusion stops, we say that the solution has reached
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equilibrium
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Molecules need a carrier protein to help them move across a membrane because they are
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lipid insoluble or they are too large
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Which of the following is true of facilitated diffusion:
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movement is passive and down a concentration gradient
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Which of the following would not affect the rate of facilitated diffusion:
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the amount of intracellular ATP
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Facilitated Diffusion:
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some molecules are lipid insoluble or too large to pass through pores in the cell's membrane, passive diffusion
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Examples of facilitated diffusion:
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sugars, amino acids, and ions
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Solutes combine with carrier-protein molecules
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in the membrane
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May have to change shape slightly to accommodate the solute, but the cell does not have to expend
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the energy of ATP
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Because facilitated diffusion relies on carrier proteins,
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solute transport varies with the number of available carrier-proteins molecules in the membrane
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Can become saturated if
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too much solute is present and the maximum transport rate is reached
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The greater the concentration difference between one side of the membrane and the other,
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the greater the rate of facilitated diffusion
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What effect do you think increasing the number of protein carriers will have on the glucose transport rate?
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Glucose transport rate increase
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What effect do you think adding NaCl will have on the glucose rate
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Decrease, to not effecting
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Are the solutes moving with or against their concentration gradient in facilitated diffusion?
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Moving with gradient (passive)
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What happened to the rate of facilitated diffusion when the number of carrier proteins was increased?
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The rate increased as well
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Explain why equilibrium was not reached with 10mM glucose and 100 membrane carriers
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The carriers were saturated and unable to carry the volume of glucose
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In the simulation you added NaCl to test its effects on glucose diffusion. Explain why there was no effect
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NaCl is not carried by glucose carriers, not slowing glucose down by using carriers
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What happened to the glucose transport rate when the glucose concentration was increased from 2mM to 8mM?
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The glucose transport rate increased
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Describe the conditions that resulted in the fasted rate of glucose transport
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700 glucose carrier proteins and 8mM glucose
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Why do you think equilibrium wasn't reached?
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The membrane proteins were saturated
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For facilitated diffusion, increasing the concentration of glucose on one side of the membrane is the same as
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Making the concentration gradient steeper
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When all of the membrane carriers are engaged, or busy, we say they are
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Saturated
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NaCl had no effect on glucose transport because
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Sodium is not required for glucose transport in the simulation
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Which of the following occurs when a hypertonic solution is added to cells?
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The cells shrink
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The variable that affects osmotic pressure is
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The concentration of non-diffusion solutes
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The net movement of water would be into the cell in a
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Hypotonic solution
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If we placed distilled water on both sides of a membrane, net movement of water does not occur, but
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water molecules would still move between the two sides of the membrane
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The concentration of water in a solution depends on
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the number of solute particle present
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Water moves toward the more concentrated solution, resulting in
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a volume increase on that side of the membrane
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Osmotic Pressure:
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the force that would need to be applied to oppose the osmosis in a closed system
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Tonicity:
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the way a solution affects the volume of a cell
Tells us wheter or not a cell will shrink or swell
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Isotonic:
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if the concentration of impermeable solutes is the same inside and outside of the cell
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Hypertonic:
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if there is a higher concentration of impermeable solutes outside the cell than in the cells interior
Cell would shrink
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Hypotonic:
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if the conectraion of impermeable solutes is lower outside of the cell than in the cells interior
Cell would swell and possibly burst
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What effect do you think increasing the NaCl concentration will have?
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Double the pressure
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What do you think will be the pressure result of the current experimental conditions?
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Medium level
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Which membrane resulted in the greatest pressure with NaCl as the solute? Why?
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20MWCO because solute wasn't able to move as fast
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Explain what happens to the osmotic pressure with increasing solute concentration
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Increases as well
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If the solutes are allowed to diffuse, is osmotic pressure generated?
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no
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Why do you think there is no pressure change?
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Sodium is able to diffuse through the pores
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Water diffused
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Toward solutes
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Filtration is a process that is
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Passive
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Filtration is dependent upon a
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Hydrostatic pressure gradient
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An import place that filtration takes place in the body is in
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The kidneys
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What effect will increasing the pore size of the filter have on the filtration rate?
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Increase significantly
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What will happen if you increase the pressure above the beaker (the driving pressure)?
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Filtration rate will increase
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Explain your results with the 20MWCO filter. Why weren't any of the solutes present in the filtrate?
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They were too large to pass through
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Describe two variables that affected the rate of filtration in you experiments
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MWCO and pressure
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Explain how you can increase the filtration rate through living membranes
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Increasing MWCO
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Judging from the filtration results, indicate which solute has the larges moleculular weight
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Powdered charcoal
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What does an increase in the driving pressure correspond to in the body?
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An increase in blood pressure
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Filatration:
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the process by which water and solutes pass through a membrane (such as a dialysis membrane) from an area of higher hydrostatic (fluid) pressure into an area of lower hydrostatic pressure
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filtrate-
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the fluids and solutes that pass through the membrane
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The amount of filtrate depends almost entirely
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on the pressure gradient (the difference in pressure between the solutions on the two sides of the membrane) and on the size of the membrane pores
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The carrier proteins in active transport are commonly called
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solute pumps
Include amino acids and some sugars
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Sodium ions are ejected form the cells by active transport
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More soutside the cell than inside the cell
Na tends to remain in the cell unless actively transported out
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Na/K pump moves Na and K in ___ _____across cellular membranes
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opposite directions
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_ NA are ejected from the cell for every _ K ions entering the cell
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3,2
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More K inside the cell than outside the cell, so K tends to remain outside the cell unless
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actively transported in
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Coupled transport:
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membrane carrier proteins that move more than one stubstance, such as Na/K pump
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Symporter:
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if the solutes move in the same direction
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Antiporter:
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if the solutes move in opposite directions
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Uniporter:
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a carrier that transports only a single solute
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What do you think will result from these experimental conditions?
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Transport of ions faster
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Do you think the addition of glucose carriers will affect the transport of sodium or potassium?
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No, glucose is transported independently
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What would happen if no ATP had been dispensed?
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No transport would happen
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Why was there no transport when you dispensed only NaCl, even though ATP was present?
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There was no K, so antiport/transport could not be completed
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What happens to the rate of transport of Na and K when you increase the number of Na K pumps?
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Rate increased
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Explain why the Na and K transporters were unaffected by the addition of glucose
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Glucose is transported independently from Na and K
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The movement of sodium and potassium maintained by the Na K pump
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Requires energy and is against a concentration gradient
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The sodium potassium pump is classified as an
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Antiporter
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Solutes that require active transport form movent might be too large to pass or might be
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Lipid insoluble
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Why did the sodium transport stop before the transport was completed?
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The ATP was depleted
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Why was the equilibrium for the solutes reached earlier?
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There were more pumps for transport
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What happened when you increased the amount of ATP dispensed with the same concentration of sodium and potassium on either side of the membrane
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More ions were transported
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What was the effect of adding more Na and K pumps to the simulated cell?
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Transport of ions was faster
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Describe the effect of adding glucose carriers to the sodium and potassium transport
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There was no change in the transport rate because glucose is transported independently
