Lisa Shaffren

Biology I

Period I- The Cell

Approximate teaching time: 50 minutes

Objective: The student will relate the cell membrane to its function in passive and active transport. (3e)

Materials: Jar, water, sugar, sodium potassium construction paper labels, board, markers

Warm-up Quiz

1) Define osmosis.

2) Make a drawing that demonstrates diffusion.

3) What does “hydrophobic” mean?

4) Is the hydrophilic region between the two layers of the cell membrane, or outside?

5) The two layers of a cell membrane, together, are called a _________________.”

Set

How do people take in food and eliminate waste? Do all living things have to use take in nutrients and eliminate waste? How do people do it? How might a cell, an entire living thing in one space, do the same thing?

It all comes back to the cell membrane. Endo and exocytosis are two of the ways that a cell membrane controls what comes in and out of a cell. Yesterday we began to relate the cell membrane its function in passive and active transport, which is what we will finish today. Review structure fits function.

Procedure:

1) Warm-up

2) Set

3) Let’s use a story to help us review the ways that we already know about a cell controlling materials that come in and out. Move through the story and write key notes- columns for each item, how it moves across, and what is represents.

Does anyone know how the boarders of a country work? Is anybody allowed to come in who wants to?

A group of people and animals is traveling across the U.S. boarder. A bird flies in and nobody notices. A squirel, a rabbit, even a bear or wolf can cross the boarder and nobody even notices; these animals slip through the pores. Why would they want to move? Maybe there is an overpopulation of squirrels, bears, wolves, or birds outside the country. (This is diffusion, or, with water, osmosis.) Quick review of hyper and hypotonic with break down of the words.)

Perhaps there is also a greater population of people outside the country, so to avoid the overcrowding people try to come in. They can’t, however, get through the pores and therefore must move through customs stations on the boarder. Some people will be allowed through but will need the help and permission of the customs officials.(Facilitated diffusion. Explain protein channels)

What about goods. We like to have trade with other countries because people here want things that we don’t make here, and people in other countries want things that we don’t use but produce to sell. These items, however, will not naturally move across the membrane because there is no concentration gradient (greater concentration gradient of a substance on one side of a membrane than the other) or the gradient is in the wrong direction. These items will have to be actively imported or exported. The country will have to go through some effort- put in some energy, to get these things in and out. (Active transport, endo and exocytosis, break down the words.

4) Diffusion demonstration with sugar and water.

5) Important to picture all of these things as functions of a cell membrane. Take five minutes and draw a cell membrane that shows each of the important functions we’ve talked about talking place. Don’t forget to draw the characteristic of the membrane that allows that to happen. Example- pores, protein channels, etc.

6) Review diagrams and have them leave in notes

7) Sodium potassium pump explanation and demonstration.

Closure: Today we related the structure and function of a cell membrane, including active and passive transport. Cold-calling questions. Tomorrow we’ll be looking at plant vs. animal cells.

Assessment:

Informal- The teacher will observe class participation.

Formal- The student will take a graded quiz on the structure and function of the cell membrane.

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