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BIS 104 PQ 5 ans Spring 2010

# BIS 104 PQ 5 ans Spring 2010 - Surface area =(4(pi(100 um 2...

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BIS 104 PQ 5 ans Spring 2010 5. Most cells that make up tissues of eukaryotic organisms are not spherical in shape. However, for the purpose of this question, let’s assume that a cell is a perfect sphere. To answer this question you must know the following: Surface area of a sphere = (4)(pi)(radius squared) Volume of a sphere = (4/3)(pi)(radius cubed) a. Calculate the cytoplasmic volume of a cell that has a diameter of 20 micrometers (20 um). Express this volume in picoliters (pl). To calc the vol in picoliters, convert units to cm, so that later, 1 cm 3 = 1 ml. So, if d = 20 um, r = 10 um or 10 -3 cm r 3 = 1 x 10 -9 cm 3 volume = (4/3)(pi)(10 -9 cm 3 ) = (4.2)(10 -9 cm 3 ) = 4.2 picoliters / cell. b. Calculate the total plasma membrane surface area of this cell.
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Unformatted text preview: Surface area = (4)(pi)(100 um 2 ) = 1.256 x 10 3 um 2 c. What do you think the approximate mass (weight) of this cell could be? Since the density of distilled water = 1.0 g/ml, and the cell is ~75% water, weight estimates can be made as follows: if cell is 100% water it would weigh 4.2 nanograms (4.2 x 10-9 grams). But since it is 75% water and 25% protein, nucleic acid, and other macromolecules that have a density greater than 1.0 g/ml, estimated weight would be something greater than 4.2 nanograms. For example, 7 – 9 nanograms / cell would be a reasonable estimate. d. What do you think is the largest cell type in your body? The smallest type? Largest = egg (oocyte) if you are female. Smallest = spermatozoan if you are male....
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