Blood Typing

Blood Typing
Background: Human blood may be classified according to the presence or absence of
certain antigens that are attached to the surface of the red blood cells. Two of the
antigens used in blood typing are known as A and B. A person whose red blood cells have
only antigen A has type A blood, whereas a person whose red blood cells have only
antigen B has type B blood. People who have both A and B antigens on their blood cells
have type AB blood.
Blood Group
Red Cell Antigen
The plasma of each blood group contains a certain type of antibodies. Anti-A antibodies
attack red blood cells that have A antigens; anti-B antibodies attack those that have B
antigens. The attacking antibodies bind to the red blood cells, causing them to clump
together. Type AB plasma has both A and B antigens and has neither type of antibody.
Type O blood has neither A nor B antigens and contains both anti-A and anti-B
antibodies. In transfusions, the blood types of the donor and recipient must be carefully
matched because the transfusion of the wrong type of blood can be fatal to the
recipient. In this investigation, you will simulate human blood typing.
Question: How is a person’s blood type determined?
Hypothesis: _________________________________________________________
Materials: 3 depression slides, simulated anti-A serum blue, simulated anti-B serum
simulated anti-Rh serum yellow, 3 mystery simulated blood samples
1. Using the dropper vial, place 1 drop of a mystery sample in each well of the blood
typing slide. Replace the cap on the dropper vial. Always replace the cap on one vial
before opening the next vial to prevent cross contamination.
2. Add 1 drop of synthetic anti-A (blue) to the well labeled A. Replace the cap.
3. Add 1 drop of synthetic anti-B serum (yellow) to the well labeled B. Replace the cap.
4. Add 1 drop of synthetic anti-Rh serum (clear-label D) to the well labeled Rh. Replace
the cap.
5. Using a different toothpick for each well, gently stir the synthetic blood and antiserum drops for 30 seconds. Remember to discard each toothpick after a single use
to avoid contamination of your samples.
6. Carefully examine the thin films of liquid mixture left behind. If a liquid remains
unchanged then there is no reaction with antibodies. If the sample appears clumpy,
agglutination has occurred. This means the antibodies have attacked the red blood
cells and destroyed them!
7. Determine the blood type of the sample using the data table below. Answer yes or no
as to whether clumping occurred in each sample. A positive agglutination, clumping,
reaction indicates the blood type. Record the results for the first blood sample in
the data table
8. Thoroughly rinse the blood typing slide, and then repeat these steps for the other
synthetic blood samples.
Data Table: Y= clumping
Sample # _____
N= no clumping
Sample # _____
Sample # _____
Blood Type
Analysis Questions:
Tom and Jane participate in a Red Cross blood drive. Both are first-time
donors. As part of the screening process, their blood is typed. Tom is A+.
Jane is AB+.
1. What blood group antibody is found in Tom’s blood?
2. What blood group antigens are found in Jane’s blood?
3. During a robbery a thief gets cut by a piece of broken glass. You are a forensic
detective called to the scene. You test a sample of blood left behind by the thief. It
is O–. While you are there, police bring in a suspect with a cut forearm who was
detained just three blocks from the store. You take a sample of the suspect’s blood
and mix it with anti-A. Immediately you know that the suspect is not the person cut
by the broken glass. How do you know the suspect is not the thief?