Exercise 1: Cell Transport Mechanisms and Permeability Worksheet Student Name: Student ID# Student instructions: Follow the step-by-step instructions for this exercise found in your lab manual and record your answers in the spaces below. Submit this completed document by the assignment due date found in the Syllabus. Rename this document to include your first and last name prior to submitting, e. g. Exercise1_JohnSmith. doc. Please make sure that your answers are typed in RED.
Grading: True/False, Multiple-Choice, and Fill-in-the-blank type questions will be worth 1 point each whereas Short-answer type questions will be worth 2 points each. This lab will be worth a total of 45 points but will be converted to a percentage grade when registered in your “Gradebook”. |ACTIVITY 1: Simulating Dialysis (Simple Diffusion) |Answers | |The molecular weight of urea is approximately 60. Which of the membranes can it pass through? D | |50 MWCO membrane | | |100 MWCO membrane | | |200 MWCO membrane | | |Both the 100 and 200 MWCO membranes | | |True or False: A solution containing glucose will diffuse faster through a 200 MWCO membrane if it|True | |is heated. | | |The molecular weight of carbon C is 12; the molecular weight of hydrogen (H) is 1; the molecular |6 x 12 = 72, 6 x 16 = 96, 12 x 1 = 12 | |weight of oxygen (O) is 16. The chemical formula of glucose is: C6H12O6 .
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Using some simple | | |multiplication and addition, determine the molecular weight of one molecule of glucose. |Total = 180 | |Describe two variables that affect the rate of diffusion. |MWCO of the membrane, molecular weight of the ion or molecule | |Why do you think that the urea was not able to diffuse through the 20 MWCO membrane? |Urea will not diffuse through the 20 MWCO membrane because it | | |doesn’t ionize | |Describe the results of the attempts to diffuse glucose and albumin through the 200 MWCO membrane. Glucose will diffuse through 200 MWCO membrane however albumin | | |will not | |Put the following in order from smallest to largest molecular weight: glucose, sodium chloride, |Sodium Chloride, Urea, Glucose, Albumin | |albumin, and urea. | | |ACTIVITY 2: Simulated Facilitated Diffusion |Answers | |True or False: The facilitated diffusion of glucose requires energy from ATP. false | |Which of the following might cause the facilitated diffusion of glucose from one solution to |D | |another to occur faster? | | |Add Na+Cl- to the beaker on the left. | | |Add K+Cl- to the beaker on the left. | | |Add ATP to the beaker on the left. | | |None of these would cause it to happen faster. | |True or False: If there are a sufficient large number of transport proteins present, glucose can |False | |be transported from a solution of lower concentration to a solution of higher concentration (i. e. | | |up its concentration gradient. ) | | |Explain one way in which facilitated diffusion is the same as simple diffusion; one way in which it|They are both passive processes; | |is different. Facilitated diffusion requires a protein carrier to travel, | | |simple diffusion doesn’t. | |The larger value obtained when more glucose carriers were present corresponds to an increase in the|The more glucose carriers there are, the less chance there is | |rate of glucose transport. Explain why the rate increased. |for saturation to set in to affect the transport of glucose. | |You were asked to predict what effect you thought that adding Na+ Cl- would have on the glucose |I predicted that nothing would happen given that Na+CL- crosses | |transport rate. Why did you pick the choice you did?
How well did the results compare with your |the membrane through simple diffusion and doesn’t need a carrier| |prediction? |like glucose. My predictions came out the way I believed it to | | |be. | |ACTIVITY 3: Simulating Osmotic Pressure |Answers | |True or False: Osmosis is considered a type of passive transport, i. e. it does not need energy |true | |from ATP. | | |If a cell is placed in a ________ solution of water, there will be no net movement of water in or |B | |out of the cell. | |hypotonic | | |isotonic | | |hypertonic | | |If you “cut” the concentration of a non-diffusible solute that is on one side of a membrane in |C | |half, the osmotic pressure will | | |double. | | |not change. | | |be half of what it was before. | | |Explain the effect that increasing the Na+Cl- concentration had on osmotic pressure and why it has |Na+Cl- will diffuse through the 50 MWCO membrane but won’t | |this effect. |through 20 MWCO. |Describe one way in which osmosis is similar to simple diffusion; describe one way in which it is |Both are passive processes, osmosis differs in that it diffuses | |different. |water through a selectively permeable membrane | |Solutes are sometimes measured in milliosmoles. Explain this statement: “Water chases |Water will diffuse to the side of the membrane that has the | |milliosmoles. ” |largest concentration of solutes. Thus “water chases solutes” | |The conditions were 9mM albumin in the left beaker and 10mM glucose in the right beaker ith the |There was no diffusion in Albumin, osmotic equilibrium was | |200 MWCO membrane in place. Explain the results. |reached. Osmotic pressure of 53 mmHg. | |ACTIVITY 4: Simulating Filtration |Answers | |The filtration rate of Na+Cl- in the simulation was dependent on |D | |the pore size of the membrane. | | |the hydrostatic pressure applied to the top beaker. | |the concentration of the solutes in the lower beaker. | | |both the pore size and the hydrostatic pressure applied. | | | |False | |True or False: The simulation would not function if the top beaker were open to the atmosphere | | |instead of having pressure applied to the top beaker. | |Explain in your own words why increasing the pore size increased the filtration rate. Use an |Just like a pasta strainer, the larger the pores in the metal | |analogy to support your statement. |the quicker and more effectively liquid will go through. | |Which solute did not appear in the filtrate using any of the membranes? |Activated charcoal | |Why did increasing the filtration pressure increase the filtration rate but not the concentration |The more pressure the faster the filtration rate will be | |of solutes? |working. However the concentration of solutes will not be | | |affected and will be the same. |ACTIVITY 5: Simulating Active Transport |Answers | |In this simulation, each of the following was (were) required In order for active transport to |D | |occur: | | |sodium ions (Na+) | | |potassium ions (K+) | | |energy from ATP | | |All of the above were required. | | |True or False: The amount of ATP that you dispensed did not affect the rate that the solutes |false | |passed from one beaker to the other. | | |Which of the following processes require ATP? E | |Simple diffusion | | |Facilitated diffusion | | |Filtration | | |Osmosis | | |Active transport | | |Describe the significance of using 9mM sodium chloride inside the cell and 6mM potassium chloride |3 Na+ are ejected for every 2 K+ ions entering the body. | |outside the cell. | | |Explain why there was no sodium transport even though ATP was present. |Both Na+ and k+ and ATP must be present for pump to function.
In| | |this simulation there was no K+ | |Explain why the addition of glucose carriers either had no effect or did have an effect on sodium |Glucose carriers had no effect on the sodium or potassium | |or potassium transport. |transport because glucose crosses the membrane by facilitated | | |diffusion and has no need for ATP | |Do you think glucose is being actively transported or transported by facilitated diffusion in this |Transported by facilitated diffusion because it is transporting | |experiment. Why? |down its concentration gradient. |