Cell Transport Mechanisms Essay

8947 Words Aug 15th, 2012 36 Pages


1:36 AM

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Cell Transport Mechanisms and Permeability
P R E - L A B Q U I Z 1. Circle the correct term. A passive process, diffusion / osmosis is the movement of solute molecules from an area of greater concentration to an area of lesser concentration. 2. A solution surrounding a cell is hypertonic if: a. it contains fewer nonpenetrating solute particles than the interior of the cell. b. it contains more nonpenetrating solute particles than the interior of the cell. c. it contains the same amount of nonpenetrating solute particles as the interior of the cell. 3. Which of the following would require an input of energy? a. diffusion b.
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The dialysis membranes used each have a different molecular weight cutoff (MWCO), indicated by the number below it. You can think of MWCO in terms of pore size: the larger the MWCO number, the larger the pores in the membrane. The molecular weight of a solute is the number of grams per mole, where a mole is the constant Avogadro’s number 6.02 1023 molecules/mole. The larger the molecular weight, the larger the mass of the molecule. The term molecular mass is sometimes used instead of molecular weight. EQUIPMENT USED The following equipment will be depicted on-screen: left and right beakers—used for diffusion of solutes; dialysis membranes with various molecular weight cutoffs (MWCOs).

Simulating Dialysis (Simple Diffusion)
1. To understand that diffusion is a passive process dependent upon a solute concentration gradient. 2. To understand the relationship between molecular weight and molecular size. 3. To understand how solute concentration affects the rate of diffusion. 4. To understand how molecular weight affects the rate of diffusion.

Experiment Instructions
Go to the home page in the PhysioEx software and click Exercise 1: Cell Transport Mechanisms and Permeability. Click Activity 1: Simulating Dialysis (Simple Diffusion), and take the online Pre-lab Quiz for Activity 1. After you take the online Pre-lab Quiz, click the Experiment tab and begin the experiment. The experiment instructions are reprinted here for your

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