A SpEGGtacular EGGsperiment!

The new unit we are working on is Unit 2: Cell Structure and Function.  So far, we have covered so much vocabulary in learning about all of the organelles and their important jobs inside of the cell.  We made fun analogies to remember these important organelles and their jobs, such as the nucleus is a CEO of a company because they are in charge of the entire cell, making sure it is functioning correctly.  Another organelle discussed was the cell membrane.  This organelle, I believe has one of the most important functions because they are like the security guards of a concert or building as they allow certain things in and out of the cell, and stops the things that shouldn’t enter or leave.  It is the protector of the cell!

Facilitated Diffusion

During class today, we learned about the many functions of the cell membrane and the different ways in which molecules may move in and out of the cell.  These types of molecular transport are passive transport, which includes diffusion, facilitated diffusion, and osmosis, and active transport.  We started our discussion with passive transport, which allows molecules to move freely across a cell membrane and does not require energy as molecules are moving down a concentration gradient, meaning molecules move from where there is high concentration of molecules, to where there is low concentration, until equilibrium is reach.  Osmosis specifically involves the movement of water through a cell membrane from high water to concentration to low water concentration, whereas diffusion includes other particles, with facilitated diffusion using a protein pump to push these particles across.  You can visualize facilitated diffusion as a security guard escorting someone into a building .

Active transport is just how it sounds, it is more active because it requires the use of cellular energy, ATP, to move molecules across a cell membrane.  This type of cellular transport moves molecules from areas of low concentration, to areas of high concentration, moving molecules up the concentration gradient and therefore needing to use energy to do it.  Imagine rolling a ball down a hill, from high to low.  It doesn’t take energy to roll a ball downhill, like it passive transport.  Now imagine rolling a ball up a steep hill.  You probably have to use a lot of ATP to do this!

To practice this new content, a choice activity was created for students.  According to Carol Tomlinson (2001), this form of differentiation allowing for students to have choice in the way they practice mastery of content allows for students to choose what is best fit for their learning style.  The choice activities included working a small group of 2 to 3 students and creating a skit with a cell transport analogy and specific reference to the types of cell transport, writing a rap or song, writing a children’s storybook, or creating a comic strip with text and drawings.  This was a highly successful activity as students were invested because they could choose how to master the material.  This was a great formative assessment as well, as I was able to analyze their choice activity work and depict any misunderstandings that may be occurring with one or several students.

Since students did so well with this new material, it is time for an at-home experiment that will help students visualize osmosis.  Don’t worry, it will be spEGGTacular!  The materials required and procedures are below.

Materials

·         1 large grade A egg

·         150 mL of vinegar

·         Large clear glass

Procedures

1.    Make observations of the egg prior to beginning the experiment

2.    Place the egg inside a large clear glass

3.    Pour 150 mL of water into the glass

4.    Make observations immediately

5.    Make observations after 24 hours of soaking in vinegar (take egg out of class)

6.    Make observations after 48 hours of soaking in vinegar (take egg out of glass)

For extra credit- complete the same experiment with corn syrup instead of vinegar!

After two days, draw conclusions based on your observations and the final result of the egg.  Why did this happen?  In which directions did molecules travel and why?  Use your content knowledge of cellular transport!

Tomlinson, C.A. (2001).  How to Differentiate Instruction in Mixed-Ability Classrooms.  New Jersey: Pearson.