Cell Talk
(Engineering Grand Challenge: Reverse Engineer the Brain)
Overview:
In this lesson, students will show their understanding of cellular communication by creating experiments to demonstrate diffusion and osmosis and a representation of endocytosis. The lesson also incorporates discussion and animations of passive and active transport, introduces students to the Engineering Grand Challenge: Reverse Engineer the Brain, and relates basic cellular transport to the function of prosthetic devices as a real life application.
Objectives:
The students will learn:

Cells are the basic building blocks of life

Some cells have specialized functions, such as neurons

In order to function, all cells must communicate with their surrounding environment

Cellular communication not only allows nutrients to pass in and out but is ultimately responsible for all movements, thoughts and sensations.
Arizona State Standards:
Strand 1: Inquiry Process

Concept 1: Observations, Questions and Hypotheses (Formulate questions based on observations that lead to the development of a hypothesis)

PO1: Evaluate scientific information for relevance to a given problem

PO2: Develop questions from observations that transition into testable hypotheses

PO3: Formulate a testable hypothesis.

PO4: Predict the outcome of an investigation based on prior evidence, probability, and/or modeling (not guessing or inferring).

Concept 2: Scientific Testing (Investigating and Modeling): Design and conduct controlled investigations

PO1: Demonstrate safe and ethical procedures (e.g., use and care of technology, materials, organisms) and behavior in all science inquiry.

PO2: Identify the resources needed to conduct an investigation.

PO3: Design an appropriate protocol for testing a hypothesis:

Identify dependent and independent variables in controlled investigations.

Determine an appropriate method for data collection

Determine an appropriate method for recording data

Concept 3: Analysis, Conclusions and Refinements (Evaluate experimental design, analyze data to explain results and propose further investigations. Design models.

PO1: Interpret data that show a variety of possible relationships between variables, including:
 positive relationship
 negative relationship
 no relationship


PO2: Evaluate whether investigational data support or do not support the proposed hypothesis.

PO4: Evaluate the design of an investigation to identify possible sources of procedural error, including:
 sample size
 trials
 controls
 analyses

Concept 4: Communication (Communicate results of investigations)

PO3: Communicate results clearly and logically.

PO4: Support conclusions with logical scientific arguments.
Strand 2: History and Nature of Science

Concept 1: History of Science as a Human Endeavor(Identify individual, cultural, and technological contributions to scientific knowledge)

PO3: Analyze how specific changes in science have affected society
Strand 4: Life Science

Concept 1: The Cell (Understand the role of the cell and cellular processes)

PO4: Analyze mechanisms of transport of materials into and out of the cells:

Passive transport

Active transport

Concept 5: Matter, Energy and Organization in Living Systems (Including Human
Systems) (Understand the organization of living systems, and the role of energy within those systems)

PO5: Describe the levels of organization of living things from cells, through tissues, organs, organ systems, organisms, populations, and communities to ecosystems
National Standards:
Standard A: Science as Inquiry

Abilities necessary to do scientific inquiry

Understandings about scientific inquiry
Standard C: Life Science

The cell

The behavior of organisms
Standard E: Science and Technology

Understandings about science and technology
Standard F: Science in Personal and Social Perspectives

Personal and community health
Materials and Resources:

Videos

The Daily Show with Jon Stewart: Interview with Medal of Honor Awardee, Army
Sgt. First Class Leroy Petry ( http://www.thedailyshow.com/watch/thu-july-14-

2011/exclusive---leroy-petry-extended-interview-pt--1 )
 i-limb: Bionic Hand ( http://www.youtube.com/watch?v=KGwGTh3grco )

Membrane Transport Examples

Facilitated ( http://www.youtube.com/watch?NR=1&v=I4123hUU8xo

Sodium-Potassium Pump ( http://www.youtube.com/watch?v=GTHWig1vOnY )

Secondary Active-Transport ( http://www.youtube.com/watch?v=Ry7l0Oe3wJM )

Activity 1: Diffusion

Large, sealable plastic bag

Balloons

Vanilla Extract (best in dropper bottles)

Activity 2: Osmosis

Beakers

Water

Salt

Potatoes

Activity 3: Endocytosis

Small paper bags

Hershey Kisses (or other small candy)

String

Scissors
Assessment:
Experimental design activities -Comprehension of diffusion, osmosis and endocytosis
Group discussion following each activity
Written test -multiple choice test at the end of the unit/chapter
Lesson Plan:
Introductory videos (10 minutes)
Tell the students that you would like them to watch the videos and make observations about what they see and how what they see might be related to what they are learning about in class (i.e. cells). Show the video of Army Sgt. 1 st
Class Leroy Petry being interviewed on the John Stewart
Show. When the video is finished, immediately show the video of the i-limb: Bionic Hand.
Open discussion (20 minutes)
Ask the students to tell you what they saw in the videos and what their general thoughts about it are. Ask them if and how they think it what they saw in the videos relates to what they are learning about cells. Using guided discussion, walk the students through how muscles react to nerve impulses, nerves are specialized cells and that they communicate with other cells and their surrounding environment by the transfer of particles across their cell membrane. This may be confusing to some students and may need to be reiterated. Once you have established that the ability to communicate and transfer material across the cellular membrane is necessary for a cell to survive, ask the students to discuss other types of membrane transport that they have heard of.
During this portion of the discussion, you should make sure to guide them through all of the

methods that you want to cover.
Follow-up videos (5 minutes)
We found that some types of membrane transport were difficult for the students to describe, or they were not as familiar with them. To help elucidate these, show the example videos listed above (or any additional videos you feel would help). Pause and/or mute the videos as necessary so that the students can note all of the important details and can walk through the process being shown with you.
Inquiry Activity 1-Diffusion (11 th
-12 th
grade: 20 minutes, 9 th
-10 th
grade: 30 minutes)
Provide brief instructions, such as “Design an experiment with the materials provided that demonstrates diffusion.” Hand out the materials (sealable plastic bag, balloon and vanilla extract) after the instructions have been given to avoid having the students play with the materials, or be distracted by them while the instructions are given. Allow them to work on the problem for 10 (11 th
-12 th
grade) or 15 (9 th
-10 th
grade) minutes. The desired experimental design is for the students to put a few drops of vanilla extract into the balloon (they only need to add about 10 drops of liquid, while the balloon is deflated), blow up the balloon, then tie it and place it into the plastic bag and seal the bag. After a few minutes, the smell of the vanilla will be very obvious in the bag. During this period of time, walk around the classroom to help guide struggling groups. Even if some groups have not finished, stop the work after the allotted time and discuss the solutions. If a group did not finish, ask them to share what their train of thought was and why they were struggling. Ask groups what their hypothesis was, etc. This activity presents a nice opportunity to discuss the concept of a selectively permeable membrane because the smell of the vanilla will diffuse through the balloon, but the liquid itself will not. Ask any other questions relevant to help clear up any remaining misconceptions.
Inquiry Activity 1-Osmosis (11 th
-12 th
grade: 20 minutes, 9 th
-10 th
grade: 30 minutes)
Provide brief instructions, such as “Design an experiment with the materials provided that demonstrates osmosis.” Hand out the (2 beakers with 50 milliliters of de-ionized water in each,
3 slices of potato of equal thickness, 10 grams of table salt and a stirring rod) after the instructions have been given to avoid having the students play with the materials, or be distracted by them while the instructions are given. Allow them to work on the problem for 10 (11 th
-12 th grade) or 15 (9 th -10 th grade) minutes. The desired experimental design is for the students to pour the salt into one of the two beakers and stir it. They should then set one potato slice to the side to serve as the experimental control, place one slice into one of the beakers containing only de-ionized water and the third potato slice into the salt/water mixture. After the potatoes have been in the solutions for about 10 minutes, the slice in the salt/water mixture will be very flimsy because the water has moved out of the potato cells and the slice in only water will be rigid and bloated because water has moved into the cells. During this period of time, walk around the classroom to help guide struggling groups. Even if some groups have not finished, stop the work after the allotted time and discuss the solutions. If a group did not finish, ask them to share what their train of thought was and why they were struggling. Ask groups what their hypothesis was, etc. This activity presents an opportunity to discuss the importance of an experimental control.
Ask any other questions relevant to help clear up any remaining misconceptions.
Inquiry Activity 1-Endocytosis (11 th
-12 th
grade: 20 minutes, 9 th
-10 th
grade: 30 minutes)

Provide brief instructions, such as “Transport a piece of food (Hershey Kiss) into the cell (paper bag) without exposing the inner membrane to the extracellular environment.” Hand out (1 paper bag, one Hershey Kiss and one piece of string) after the instructions have been given to avoid having the students play with the materials, or be distracted by them while the instructions are given. Allow them to work on the problem for 10 (11 th
-12 th
grade) or 15 (9 th
-10 th
grade) minutes. The desired action is for the students to simulate endocytosis by pushing the Hershey
Kiss into the side of the bag and have the bag envaginate to form a vacuole around the candy, then using the string to re-secure the membrane (paper bag). They should not simply drop the candy into the bag through the top. During this period of time, walk around the classroom to help guide struggling groups. Even if some groups have not finished, stop the work after the allotted time and discuss the solutions. If a group did not finish, ask them to share what their train of thought was and why they were struggling. Be sure to discuss the difference between endocytosis and exocytosis, pinocytosis and phagocytosis and any other terms or words necessary to fully explain the process. Ask any other questions relevant to help clear up any remaining misconceptions.
Review/Reflection (5-10 minutes)
Take a few moments to revisit all of the different types of membrane transport covered and answer any outstanding questions. Point out that these simple interactions of the cell are responsible for much more complex functions and activities that we use everyday, such as muscle movement. You may consider asking topics that the students can relate to real life, such as, “If you mother sprays air freshener in the living room while you are working at the dining room table with headphones on, how might you know that she just sprayed something?”, “If you eat a bag of salty chips and have not had any water that day, what might be happening to some of your cells?”, or “Why do salty foods make us thirsty?”.