MOLECULES PRESENTATION

MOLECULES

14. Fehling's solution b

7. A measuring cylinder

13. Fehling's solution a

6. An eletronic balance

12. Iodine solution

5. Gluocose powder

11. Two pipettes

4. Potato starch

10. A spoon

3. Distilled Water

9. Bag clips

2. Two glass beakers

8. A paper tray

1. Two small Semi-permeable bags

INDEX

Objective

To simulate the funcions of a semi-permeable cell membrane. To explare the differences in the movement of molecules into and out of a semi-permeable membrane.

Introduction

"In this experiment the complex molecules, or polymers, such as starch, cannot move across a semi-permeable membrane, while small molecules, or monomers, such as glucose, are able to pass through."

"Larger molecules, like glucose and mineral ions, use special channels in the cell membrane to enter and leave the cell. In contrast, a complex carbohydrate such as starch would be simply too large pass through the membrane."

" The cell membrane has different properties. The cell wall gives strength and support to a plant cell and allows substances to move in and out freely. The cell membrane, however, has a more flexible structure and has smaller gaps between its phospholipid molecules, which only allow small water molecules to move in and out. "

STEP 1

Pour 50 ml of distilled water measured into a graduated cylinder into the two glass beakers.

Measure 5 grams of sugar to 5 grams of flour with an electronic scale and place the two quantities in two small containers.

STEP 2

STEP 3

Take 2 ml of Fehling's solution a and Fehling's solution b and pour them into the first glass beaker.

Take 1 ml of Iodine solution and pour it into the second glass beaker.

STEP 4

Insert the 5 grams of sugar into a small Semi-permeable bags and add 20 ml of distilled water, then close it with bag clips and place it in the glass beaker containing the water and Fehling's solution a/b.

STEP 5

Insert the 5 grams of flour into a small Semi-permeable bags and add 20 ml of distilled water, then close it with bag clips and place it in the glass beaker containing the water and iodide solution.

STEP 6

Results

Here are the results after waiting two hours.

Deepening

Heating the beaker to a temperature of about 40 degrees Celsius will change color.

Team

EMANUELE MEMOLI

VITTORIO MANZO

DAVIDE APICELLA

Thanks!

We can observe that in the first case (Fehling's solution a/b) the molecules exit but do not enter while in the second (iodine solution) the molecules enter but do not exit.