Blood Typing Activity
Fundamental Question: Can blood type be determined from an unknown sample?
Introduction:
Human blood may be classified according to the presence or absence of certain antigens,
or factors, that are attached to the surface of the red blood cells (erythrocytes). 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 red blood cells have type AB blood.
Those whose blood cells have neither A nor B antigens have type O blood.
The plasma of each blood group contains a certain type or combination of antibodies.
Antibodies are substances that attack antigens. Blood type A plasma contains anti-B antibodies,
whereas blood type B plasma has anti-A 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 agglutinate (clump together). Type AB plasma has
both A and B antigens and has neither anti-A nor anti-B antibodies. 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 the recipient must be carefully matched
because transfusion of the wrong type of blood can be fatal to the recipient. Usually, before blood
is given from one person (donor) to another (recipient), the red blood cells are separated from the
plasma. That way, the donor is providing red blood cells without the antibodies and the only
concern is whether or not the donor antigens will be attacked by the recipient’s antibodies.
Refer to pages 344 and 954 in your textbook for a visual depiction of the above
information as well as the diagram below. In this activity, you will simulate human blood typing.
Materials:
simulated anti-A sera, simulated anti-B sera, simulated blood (three samples of unknown type),
distilled water, microscope slide, hand lens
Procedure:
1. Using the information about blood on page 1, create a blood typing chart like the one
below in the lab section of your science notebook. Use a “+” symbol to indicate a positive
clumping reaction and a “-“symbol to indicate no clumping (a negative result). Hint: if
the antigens on a blood cell fit together with the antibodies of sera (Anti-A or Anti-B) then
they will clump.
Blood Type
Clumping in anti-A antibodies
(anti-A sera)?
Clumping in anti-B antibodies
(anti-B sera)?
A
B
AB
O
2. Have your teacher check your table for accuracy (get a stamp or signature). The table that
you’ve just made is your blood typing key; you will use it to analyze experimental results
and determine the blood types of three unknown patients.
3. Put on safety goggles. Place 1 drop of the solution in the dropper bottle labeled “Anti-A
sera” on the left side of a microscope slide. Place 1 drop of distilled water (as a negative
control) in the center of the microscope slide. Place 1 drop of the solution in the dropper
bottle labeled “anti-B sera” on the right side of a microscope slide.
4. Add 1 drop of the Person W blood into the anti-A sera on your slide (left side). Add 1
drop of person W blood to the water drop (center). Add 1 drop of the person W blood into
the anti-B sera on your slide (right side). Important: do not let the blood samples touch the
anti-A or anti-B sera (they can contaminate them).
5. Wait at least five minutes. Examine the two solutions for signs of clumping (you may
need to put the slide on white paper and/or use a hand lens) as compared to the water
control. Record your results in a table like the one below in the lab section of your science
notebook. Rinse off your glass slide and dry with a paper towel.
6. Repeat steps 3-5 for the remaining two unknown blood types so that you have data for all
three unknown people (W, X and Y).
7. Use the blood type table that you created using the background information to determine
the blood types of all three patients.
Patient Sample (W, X or Y)
Clumping in the
left side (anti-A)?
Clumping in the
right side (anti-B)?
Blood Type
Questions: Answer ALL questions in the lab section of your journal IQIA.
1. Which blood type(s) show clumping when added to anti-A sera?
2. Which blood type(s) show clumping when added to anti-B sera?
3. If clumping occurs when both anti-A sera and anti-B sera are added, what is the blood
type?
4. If clumping does not occur when both anti-A sera and anti-B sera are added, what is the
blood type?
In blood transfusions, the red blood cells are separated from the plasma. That way, the donor
is providing red blood cells without the antibodies and the only concern is whether or not the
donor antigens will be attacked by the recipient’s antibodies.
5. Which blood type(s) must people have in order to safely receive a transfusion from type
A blood?
6. Which blood type(s) must people have in order to safely receive a transfusion from type
B blood?
7. Which blood type(s) must people have in order to safely receive a transfusion from type
AB blood?
8. Using the pedigree above, identify the genotypes of both individuals labeled 1 and 2.
9. Assuming that individuals 1 and 2 are in a car accident and need blood, which of your
patients (samples identified earlier) can donate blood to individual 1? Individual 2?
Explain your reasoning using data from the simulation to support your statements.
10. Assuming that the patients (samples identified earlier) are in a car accident and need
blood, to whom can individual 1donate blood? Individual 2? Explain your reasoning
using data from the simulation to support your statements.
Your answers to questions 11-13 should include mention of antigens and antibodies.
11. Why is a person with type AB blood sometimes called the “universal recipient”?
12. Why is a person with type O blood sometimes called the “universal donor”?
13. Why is a person with type O blood unable to receive blood from any type other than O?