Karen A. Beitler
(Note to Teachers: these activities were formatted for this paper; please copy and reformat with spaces for use with your students; for answers to questions or PPT email karen.beitler new-haven.k12.ct.us and I will send them to you.)
Lab Activity 1 - How particles move
Sand & Sieves and Electrophoresis
Objectives
1. Explain how molecules move through a semi-permeable membrane
2. Define diffusion and osmosis
3. Observe electrophoresis of molecules of different sizes.
Background
Molecules are not all the same size. It is often difficult to envision diffusion and understand electrophoresis because the different size molecules are not visible. This activity will involve a teacher demonstration and a student lab to demonstrate the process of diffusion of molecules.
Electrophoresis is a process that uses electricity to separate different size molecules for identification. A group of proteins in blood plasma are often identified this way in order to diagnose or monitor a variety of serious illnesses. Electrophoresis takes advance of the movement of electrically charged particles under the influence of an electric field. The force on molecules in an electrical field is called the , this force moves at right angles to an electrical field. The process is also used in amplifying and sequencing genes, detecting mutations, detecting infection and drug development.
Initial Observations; (What do I know?)
Prelab Questions (Homework);
Vocabulary: Define electricity, protein, buffer, sieve
Research question: What is electrophoresis and how is it used?
Procedure I: Teacher demonstration
1. Materials; electrophoresis chamber, electrophoresis power supply, pre-made agar gel, buffer solution, commercial food colors, pipette and tips
2. Make a written record of which sample you will load in each well of the gel. You may find it helpful to load samples in every other well.
3. Place the gel form on a black or dark surface to help you see the wells in the agar. Be
careful not to puncture the bottoms of the wells as you load the samples.
4. Place the gel in the electrophoresis chamber.
5. Make sure that the wells are closest to the negative (black) electrode.
6. Prepare the buffer solution and add it to the chamber.
7. Place the lid on the chamber and connect the electrode leads to the power supply.
8. Connect the black lead to the negative terminal and the red lead to the positive terminal.
9. Turn on the power supply and adjust the voltage to 50-100 volts.
10. Run the gel for 5-10 minutes. Observe the samples separating into different colors.
11. Turn off the power supply, disconnect the electrode leads, and remove the chamber lid.
12. Remove the gel from the electrophoresis chamber and analyze your results.
13. Record and evaluate the results of the electrophoresis.
14. Analyze and write a summative conclusion
Make Some Predictions
1. What will happen when the sand is poured through the sieve?
2. How does pouring sand through a sieve demonstrate how molecules move through a gel?
Procedure II: Student activity
1. Materials; 3 sieves of different size screen, sand, scale and 2 weighing trays.
2. Weigh out 10 grams of sand.
3. Pour the sand through the screen with the largest holes onto a new weighing tray;
weigh and record weight of the sand that went through the screen.
4. Pour the weighed sand through the second screen; collect onto a weighing tray and
weigh the sand that went through and record.
5. Pour the weighed sand through the last screen; onto a clean weighing tray. Weigh and
record.
6. Analyze data and make a summative conclusion; relate your activity to the teacher demonstration.
Questions:
1. What does each of the following represent in this experiment?
a. the sand represents __________________ because ________________________________________________________________.
b. the screen represents _________________________because ________________________________________________________________________
2. What happens to the sand as it passed through the screens?
3. How is this procedure similar to electrophoresis? How is it different?
Date Table 1_________________________________________
(table available in print form)
Post Lab Analysis
1. Based on your observations of the teacher demonstration, what happened to the dyes?
placed in the wells at the positive (red) end of the chamber?
2. What forces helped the dyes to move?
3. Why did some colors move farther towards the positive pole than others??
4. Describe how gel electrophoresis could be useful in police work.
Lab Activity 2 Diffusion and Transdermal Patches
Diffusion of Medication
Objectives
1. Explain facilitated diffusion of a substance across a semi permeable membrane
(potato)
2. Use indicators to determine the presence of a substance
3. Observe equilibrium
4. Show how medication travels through cell
Initial Observations ;( What do I know?)
Prelab Questions (homework);
1. Define facilitated diffusion, equilibrium and indicator.
2. What happens when iodine comes in contact with starch?
Procedure
1. Materials; evaporating dish, Petri dish or small beaker, forceps, slice of potato, paper towel, Lydol's iodine solution, eyedropper, 50% Vitamin C solution, adhesive bandage, small knife, stop watch or clock, clear ruler
2. Read all lab procedures.
3. Use forceps to put the potato slice into the evaporating dish, pat dry with a paper towel if it has been soaking in water
4. Use the knife to make small cut in the potato.
5. Using an eyedropper to place one drop of iodine in the center of the cut, measure the size of the drop immediately, note any color change, and start a timer.
6. While you are waiting, answer the lab questions
7. Make observations at 5, 10, and 15 minutes; measure the size of the drop and examine all sides of the potato each time using the forceps to turn it.
8. Record observations in the data table
9. After fifteen minutes, use the forceps to add 3 drops of Vitamin C solution to the adhesive bandage. Place the bandage over the cut.
8. Make observations as before at 5, 10, and 15 minutes: record size of color change circle
9. Set the potato in a safe place for 24 hours.
10. Make a final observation and record
Make Some Predictions
1. Are the potato cells permeable to iodine? How do you know?
2. What do potato cells contain? How does the iodine help you show this?
3. What do you think will happen with the size of the drop of iodine as time goes by?
4. What will happen to the iodine when the Vitamin C is added?
5. If the iodine was a germ that attacked starch cells; predict what the Vitamin C would do.
Questions:
1. Define diffusion:
2. Define equilibrium
3. Molecules tend to move from areas of _______ concentration to areas of ______
concentration. What is the main difference between osmosis and diffusion?
4. Why is iodine called an indicator? What color is iodine? What does it indicate?
5. When the iodine is dropped on the potato what color is it? Does it change color? Why?
6. What does each of the following represent in this experiment?
a. the potato represents _________________________ because ______________________________________________________________________.
b. the iodine represents _________________________because
______________________________________________________________________.
c. the Vitamin C represents ______________________because
______________________________________________________________________.
7. What happens to the iodine when the Vitamin C solution is placed on it?
Data Table_________________________________________________
(table available in print form)
Observation after 24 hours:
Post Lab Analysis
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1. Based on your observations, which substance moved, the iodine or the starch?
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2. How did you determine this?
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3. The potato slice was permeable to which substance?
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4. What happened when the Vitamin C solution was placed on the iodine/starch complex?
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5. Sketch potato, bandage with Vitamin C solution tablet below in the space below. Use arrows to illustrate how diffusion occurred in this lab.
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6. Describe a scenario where germs enter the skin through a break in it. What happens when the medicine is delivered to the site?
Lab Activity 3 - Drug Delivery inside the heart
Delivering drugs with a stent
Objectives
1. Define percutaneous coronary intervention
2. Describe the mechanism of a heart attack
3. Demonstrate insertion of a catheter, stent and angioplasty balloon
4. Observe expansion of a stent
5. Explain how drug-eluting stents can be used deliver medication
Background observations
Advances in the field of biomedical technology have led to better treatment for patients with blocked arteries. In the last activity you saw how medication can be delivered by applying it to the skin it travels into the body. In the event of a heart attack, where a blockage is the cause, the goal is to restore blood flow to the heart muscle in as little time as possible. In the past few years there have been dramatic advances in the techniques and devices used open an artery. This simple lab simulation will help demonstrate the overall procedure in "balloon" surgery.
What is a heart attack? The medical term for heart attack is myocardial infarction; a heart attack is when the blood supply to the muscle in the heart is restricted or stopped. This happens when an artery leading to the heart (coronary artery) is blocked. The blockage is often caused by a build up of a fat-like substance called plaque. The process of plaque build up is called atherosclerosis and is caused by layers of fat, cholesterol, calcium, and other substances found in the blood lining the arteries. As it grows, the buildup of plaque narrows the inside of the artery and, in time, may restrict blood flow. Plaque deposits can burst, rupture, or block an artery- this leads to a heart attack. If the supply of blood to the heart is cut off for more than a few minutes, heart muscle will have permanent damage; this can disable or even kill someone.
When a surgeon makes a recommendation for a patient to have a percutaneous coronary intervention he is basically saying that a catheter (a thin, soft, flexible tube that can expand and will allow things to go through without damage to the insertion point) will be inserted into an artery of the body, usually near the heart. Depending on the severity of the blockage the catheter may deliver a wire mesh sleeve, called a stent, which would be left in place to hold the artery open, and the stent may also be coated with plaque dissolving drugs. What the catheter does deliver is a balloon which can be slowly inflated to unblock the artery and restore blood flow. A polymer infused with medication is 'painted' onto the stent. The medication is slowly released into the artery delivering plaque-dissolving medication as the polymer itself is broken down by the body's natural processes.
Initial observations; (What do I know?)
Pre-lab Questions (homework)
1. What is a heart attack?
2. What causes arthrosclerosis?
3. How does plaque cause a blockage?
4. What is a catheter?
5. How does a stent help in an angioplasty
6. What are ways of dissolving plaque inside an artery?
Procedure:
1. Materials; 8x11 sheet of paper, tape, snack bag with ends cut off, straw, small balloon, soft measuring tape, tissue paper or scraps
2. Cut a strip of paper 14 cm x 28cm.
3. Fold the paper 1 cm along the 14 cm end, crease. Turn the paper over and fold it back 1 cm.
4. Continue to fold in this manner until you have folded and creased the whole length.
5. Tape one end of the folder "fan" to the other along the entire length so that you have a folded cylinder. Measure the circumference of the folded cylinder; record.
6. Set this aside and stretch your balloon, blow air into it a few times to be sure it will expand.
7. Cut the ends off the sides of a small snack baggie and 'clog' the 'artery' with two or three 5 cm squares of tissue or scrap paper. Measure the circumference of your artery.
8. Insert a straw half way into a balloon, seal with a small piece of tape. Measure the circumference of the straw; record.
9. Make a prediction about what you think will happen when your balloon and stent are inserted into your 'artery'…
10. Carefully insert the straw, balloon side first, into the paper cylinder about one half the ways. Measure the circumference of the paper cylinder with the balloon inserted.
11. Slowly slide the paper cylinder with a balloon and straw inside the plastic bag.
12. Holding the bag in your hand, slowly blow into the straw to inflate the balloon.
13. Observe how the paper cylinder expands. Measure the circumference of the plastic bag with the paper cylinder inflated; record.
14. Remove the straw/balloon; Measure the circumference of the plastic bag; record.
15. Describe the procedure you have just demonstrated in a 200-400 word essays, using the new medical terms you have learned. Include answers to the questions below.
Questions:
1. What is a percutaneous coronary intervention?
2. What is a heart attack?
3. How do doctors try to prevent heart damage in the event of a blocked artery?
4. Describe the balloon angioplasty procedure
5. What does each of the following represent in this experiment?
a. the folded paper cylinder represents _______________ because
___________________________________________________ .
b. the balloon represents ________________________because
___________________________________________________.
c. the straw represents _________________________because
____________________________________________________.
d. the plastic bag represents _____________________because
____________________________________________________.
6. How does this simple activity demonstrate the angioplasty procedure performed when an artery is blocked?
Lab Activity 5 - Career Path Research
Career path research- library & web research; presentation
Careers in Biotechnology-- student questions
1. What is biotechnology?
2. What are some possible careers in biotechnology? - Choose one for research
3. What is a (your choice)?
4. What are some of the specialty things this person does?
5. Where do these people work?
6. What does the future demand look like for this type of career?
7. How should I prepare for a career in (your choice)?
8. How do I select a biomedical engineering academic program?
9. What is the difference between the various degrees offered in this field?
10. What are some little known facts about your choice of field?
11. Helpful resources ( minimum 3)
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1.
Careers in Biomedical Engineering
found at http://www.bmes.org/careers.asp
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2. http://www.competitionmaster.com/pages/career/careers_in_biotechnology.html
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3. http://www.biotechnologyonline.gov.au/
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4. http://www.morst.govt.nz/wayfinder/