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Biology-Mr.Willets
Lab-Blood Types
The basic human blood type groups (ABO) are controlled by a genetic situation known as multiple alleles. There are three genes that control blood groups: IA (gene for type A) , IB (gene for type B), and i (gene for type O) . Each person has a pair of genes and depending on exactly what that pair is like, each person has a certain blood type. The various combinations will be discussed in class.
If you have type A blood, your red blood cells have on their cell membrane a chemical called the A antigen. If you have type B blood, you have the B antigen. If you are type O, you have neither antigen. If you are type AB, your red blood cells have both the A and the B antigens.
People with type A blood also have in their blood a chemical which reacts with the B antigen. This chemical that Type A people have is called the Anti-B antibody. It is there because the B antigen is considered foreign material and therefore must be attacked. People with type B blood have the Anti-A antibody. People with type O blood have both the Anti-A and the Anti-B antibodies. People with type AB have neither antibody. Think about why the last two cases are so.
When transfusions are given, we must be careful not to mix bloods that would cause a reaction. In all the cases, the receiver's blood cannot contain antibodies that would attack the donor's antigens. In the chart below, for each blood type indicate 1) what antigen the blood has, 2) what antibodies it has, 3) what blood types it would fight against 4) what blood types it can receive and 5) what blood types it can be a donor for
Note- a person can receive any blood type that he doesn't have antibodies against. A person can donate blood to any person that does not have antibodies that fight it.
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To find out what blood type a person has, a sample of blood is mixed with Anti-A antibody. If a reaction occurs, this means the blood contains the A antigen (type A blood). Another sample is then mixed with Anti-B antibody. If a reaction occurs, this means the blood contains the B antigen (type B blood). If a reaction occurs in both cases, both antigens are present (type AB blood). If no reaction occurs in either case, neither antigen is present (type O blood).
The reaction that occurs is one that makes the red blood cells sticky and thousands of them will clump together. This can be seen easily without magnification. Note- clumping is not the same as clotting. The fancy name for clumping is agglutination.
We can no longer use actual blood for fear of spreading disease but we will use some harmless chemicals that will react the same as real blood and real antibodies. The clumping may not be as obvious so if in doubt, use scanning power to be sure.
Procedure-
1) Get a slide and a toothpick.
2) Place the slide on this sheet so it has a white background. Add a drop of Anti-A antibody to the slide.
3) Add a drop of simulated blood to the slide. Drop it on. Do not touch the tip of the dropper to the chemical already on the slide. Whose "blood" did you use? ___________________________
4) Use the toothpick to thoroughly mix the blood with the Anti-A antibody. Scrape the toothpick along the slide as you do this. Continue to mix for two minutes or until clumping is seen. If you don't mix thoroughly, you may get an incorrect result. Did clumping occur?____________ THROW AWAY THE TOOTHPICK!!
5) Clean the slide thoroughly and put a drop of Anti-B antibody on the slide. Add a drop of the same person's "blood" and mix as before. Use a new toothpick. Did clumping occur? ______________ Again, THROW AWAY THE TOOTHPICK!!!!!
Blood sample from ____________________________ Blood type? __________
6) Repeat this whole procedure with a second person's "blood".
Clumping with Anti-A? ______ Clumping with Anti-B?_________
Blood sample from______________________________ Blood type?__________
The results for the 4 "people" whose blood we typed will be put on the board.
Jane Doe _______ John Doe, Sr. ________ John Doe, Jr._________ Wiley Smith _________
John Doe thinks his wife has been unfaithful. He has asked you as an expert geneticist to prove it. (Wiley Smith is the mailman.) Submit your report to me. Use a separate sheet. I will pass it along to him.
Your report should tell him :
A) if he could be the father or if he could not- use 2 Punnett Squares to make your argument. One assuming Jane is pure A, the other assuming she is hybrid A.
B) if he is not the father, you should tell him if Wiley could be the father or not. Find one Punnett Square that proves your point.
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