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Lab: All Name Passive Transport Date pd. Diffusion of Molecules Across a Eukaryotic Cell Membrane Introduction: You have seen how molecules act when contained by simulated cell membranes. The following experiment will allow you to use an animal cell as an experimental subject to see if eukaryotic cells actually behave the same as simulated cell membranes. You will first remove the calcium shell that surrounds a chicken egg to expose the plasma membrane. You will take the mass of each egg and then soak each egg in a separate solution—one solution containing charged ions (vinegar), another solution containing small, uncharged molecules (water), and a third solution containing larger uncharged molecules (sucrose). I. Purpose: Which molecules will enter a real cell membrane and which are kept outside the membrane. II. Hypothesis: a. I think the eukaryotic animal cell will (write: allow / not allow) the small, charged vinegar ions to pass through the cell membrane. b. I think the eukaryotic animal cell will (write: allow / not allow) the small, uncharged water molecules to pass through the cell membrane. c. I think the eukaryotic animal cell will (write: allow / not allow) the larger, uncharged sucrose molecules to pass through the cell membrane. III. Experiment a. Materials (see attached) i. 3 eggs; 3 beakers; 3 spoons; 160ml of white vinegar; distilled water; 100ml graduated cylinder; 80ml of 1M sucrose; Parafilm or cling wrap; funnel, paper towels. b. Procedure (see attached) 1) Label three plastic cups with your lab group name, period, and label each with one of the following: vinegar, syrup, water. 2) Obtain 3 eggs, place them into its designated plastic up. Take the initial mass and write the data in the data chart. 3) Add 50ml of vinegar to all three plastic cups. If more vinegar is needed to cover the raw egg, add 10mL at a time. 4) Let them sit undisturbed for two days. STOP! END OF DAY 1! 5) Start of day 2! Break up the work to get it done faster! 6) Obtain a graduated cylinder and a funnel. Pour out the vinegar from cup 1 through the funnel into the graduated cylinder. Be careful NOT to let the egg fall out. Eventually remove the egg from the cup and pour out the rest of the vinegar from cup 1 into the cylinder. Record the new volume in the data chart. 7) Rinse out and dry the plastic cup. 8) Under running water, or in a tub of water, gently rub the egg in your hands until all of the shell is rubbed off and the egg is left with only the opaque plasma membrane holding in its contents. Do not rub too vigorously or the egg will burst. Gently pat each egg dry 9) Roll the egg gently back into its designated cup. 10) Take the new mass and write it on your data table. 11) For the FIRST egg in cup #1, add 50ml of vinegar. If the egg is not completely covered, add 10ml at a time, until it is covered, keeping track of the total volume added to the beaker. Record the total volume added to the cup in your data table. 12) For the SECOND egg in cup #2, add 50ml of syrup. If the egg is not completely covered, add 10ml at a time, until it is covered, keeping track of the total volume added to the cup. Record the total volume added to the beaker in your data table. 13) For the THIRD egg in cup #3, add 50ml of WATER to the beaker. If the egg is not completely covered, add 10ml at a time, until it is covered, keeping track of the total volume added to the beaker. Record the total volume added to the beaker in your data table and on your cup. 14) Let the eggs sit in their corresponding cups for one day. STOP! END OF DAY 2! 1) Start of day 2! Break up the work to get it done faster! 2) Place a funnel on top of a graduated cylinder. Pour the vinegar from cup 1 through the funnel into the graduated cylinder. Hold the egg back. Try to get as much of the vinegar as possible to get an accurate reading. Eventually remove the egg so that the rest of the vinegar can be measured in the graduated cylinder. Record the final volume that was in cup #1 on your Data Chart. 3) Rinse out and dry the plastic cup. 4) Dry the egg as much as possible. Be careful NOT to break it! 5) Record the new final mass of the egg in cup #1 into your data chart. 6) Repeat steps 1-5 for the water and the syrup. 7) Throw the eggs into the trash can. Wash and dry all 3 cups and place cups into the cabinet. Wash graduated cylinder and funnel with soap and water. 8) See me for a cleanup grade __________________ (Henriques initial) 9) Calculate your group data and class data You will TYPE out a formal lab report for this lab! In the experiment section (materials and procedure) typing out the statement “(see attachment)” will excuse you from retyping out the entire experiment section as long as this original paper is attached to the formal lab report. In the organizing data section (recorded, processed and graph) typing out the statement “(see attachment)” will excuse you from retyping out that entire section as long as this original paper with all data, calculations, and graph is attached to the formal lab report. Be sure the lab report is… 1. Typed with Times New Roman, 12 font size, single spaced. 2. Margins are 0.5-1.0 inch. Initial Set up Egg in Egg in Egg in (DAY 1 AND DAY 2 DATA) Vinegar cup Syrup cup Water cup o Initial beaker volume (ml) o Final beaker volume (ml) o Percent change in volume = (Initial - final)/final o Initial mass (g) o Final mass(g) o Percent change in mass = (Initial-final)/final Lab Group Data Chart Egg in Egg in Egg in (DAY 2 AND DAY 3 DATA) vinegar sucrose water o Initial beaker volume (ml)…see day 2 o Final beaker volume (ml)…day 3 o Percent change in volume = (Initial - final)/final o Initial mass (g)…see day 2 o Final mass(g)…day 3 o Percent change in mass = (Initial-final)/final Class Data Egg in vinegar Egg in syrup Egg in water Chart % change in % change in % change in % change in % change in % change in volume mass volume mass volume mass Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Class average The following questions will be added into the conclusion section of your typed formal lab report. Answer in complete sentences, numbered as follows (do not type out the questions). 1) What was the purpose of this experiment? 2) What topic does this experiment allow us to test? 3) Why were the eggs placed in vinegar for two days? 4) Name two reasons sucrose was used as one of the three test solutions? 5) Name two reasons water was used as one of the three test solutions? 6) Is this cell alive? Can it perform active transport? 7) Not all eggs were the same size at the beginning of the experiment, which means some eggs were able to take in more solutes simply because they had a greater surface area. How do we account for differences in the size and surface area of each egg? 8) How does the percent change in volume relate to the percent change in mass? 9) Restate your hypothesis (complete sentences). 10)Which solutes were able to pass through the plasma membrane of the eukaryotic cell? 11)Is this eukaryotic animal cell membrane selectively permeable? Support your answer using your data. 12)What conclusion can you make about other eukaryotic animal cells?
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