Essay on Effects of Temperature and Solvents on the Cell Membrane

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SOTM LAB: B14 12/99

I. TEACHER NOTES & GUIDELINES

Title of Lab: Effects of Temperature and Solvents on the Cell Membrane

Developers of Lab: Adapted by James Kirby JD726, Jennifer Mortellaro JD449, and James Prockup JD575 from a publication by the Department of Biological Sciences at Western Michigan University, Kalamazoo, MI

Overview of Lab: Description: The purpose of this lab is to illustrate the effects that temperature and solvents have on the cell membrane.

Red beet tissue contains large amounts of betacyanin, a red pigment, located in the large internal membrane vacuoles. When the membrane is damaged, this pigment can cross the vacuole membrane and cell (plasma Membrane). In
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Be specific.

DISCUSSION OF PRECONCEPTIONS Have one person, from each group, discuss with the class the group’s answer to each question.

III. EXPLORATION OF SCIENTIFIC PRINCIPLE & INTRODUCTION OF EXPERIMENTAL PROTOCOL

PROBLEM What effect will temperature changes have on a membrane?

EXPERIMENT AND TECHNICAL OOPERATION OF EQUIPMENT

PROCEDURE

1. Cut 5 uniform cylinders of beet using a cork borer with a 4-mm inside diameter. Line up the pieces, cut off the ends and make another cut to obtain 15-mm long pieces (all pieces must be the same size). 2. Rinse each piece for 2-min in a large beaker of tap water to remove the excess red dye that leaked during the cutting procedure. 3. Place one piece into each of the 6 test tubes and write a number on the tube/lid with a marker. a) Frozen (from teacher) b) On ice for 15-mins c) 25C (room temp) for 15-mins d) 37C (hold in your hand) for 15-mins e) 55C for 15-mins f) 80C for 15-mins

4. After temperature treatments, add 5-mL of distilled water, cover with parafilm and allow to stand for 15-mins. During this time the teacher will preview with you the operation of the spectrophotometer. Invert the tubes gently several times during the 15-mins. 5. Pour the liquid from test tube (a) into a clean cuvette. Wipe down the outside of the tube, and