Ms. Buchalski
1
Honors Biology
Name _____________________
Period _______
CSI Blood Typing Lab:
“Who Dun It?”
Background Information:
There are many different ways to classify blood types, but the most common blood type
classification system is the ABO system. There are four blood types in the ABO system: Type A, Type
B, Type AB, and Type O. Each of the 4 types may also be considered “positive” or “negative”. These
blood types refer to different versions of carbohydrate molecules which are present on the surface of
red blood cells (a.k.a. surface antigens).
Have:
People with:
Type A carbohydrate molecules
on their red blood cells
Type A blood
Type B carbohydrate molecules
on their red blood cells
Type B blood
Type A and B carbohydrate molecules
on their red blood cells
Type AB blood
Neither A nor B carbohydrate molecules
on their red blood cells
Type O blood
The Type A and Type B carbohydrate molecules are called antigens because they can stimulate the
body to produce an immune response, including antibodies. Antibodies are special proteins that
travel in the blood and help our bodies to destroy viruses or bacteria that may have infected our
bodies.
Ms. Buchalski
Honors Biology
2
Adapted from Figure 40.5 in Holt Biology by Johnson and Raven
Normally, our bodies do not make antibodies against any molecules that are part of our own bodies.
Thus, antibodies help to defend against invading viruses and bacteria, but normally antibodies do not
attack our own body cells.
For example, people with Type A blood do not make antibodies against the Type A antigen which is
present on their red blood cells, but they do make antibodies against the Type B antigen. Test your
understanding of blood groups by filling in the blanks in the chart below.
Blood group A
If you belong to the blood group A, you have
A antigens on the surface of your red blood
cells and _______ antibodies in your blood.
Blood group B
If you belong to the blood group B, you have
B antigens on the surface of your red blood
cells and _______ antibodies in your blood.
Blood group AB
If you belong to the blood group AB, you
have both A and B antigens on the surface of
your red blood cells and no anti-A or
anti-B antibodies in your blood.
Blood group O
If you belong to the blood group O, you have
neither A nor B antigens on the surface of
your red blood cells, but you have both
______ and _____ antibodies in your blood.
Ms. Buchalski
3
Honors Biology
Who Dun it?
Instructions:
Uh oh! Someone has been murdered! Now that you have learned about blood and blood typing the
cops need YOU to help them figure out who dun it. Luckily for you the murderer was sloppy. He left
some blood behind at the crime scene. Don’t get confused though because the victim lost a lot of
blood as well. The detectives have a few suspects but need your help to decide who to arrest for the
crime. They have collected samples of blood from each of the suspects and also collected some of
the blood found at the crime scene. It is your job to perform a blood typing test in order to determine
who committed the crime. Follow the steps below to perform the test.
Procedure:
Step 1: Collect your materials. You will need a well plate and a handful of toothpicks. Make sure you
have each of the different suspects’ blood as well as the victim’s blood and the blood found at the
crime scene. You will also need the different anti-serums (Anti-A, Anti-B, Anti-Rh).
Step 2: Place 3-5 drops of the patient’s blood into all of the wells in the first well plate. Place 2-3
drops of Anti-A antiserum into the well labeled “A”. Then place 2-3 drops of Anti-B antiserum into the
well labeled “B” and Anti-Rh antiserum into the well labeled “Rh”.
Step 3: Use a different toothpick to stir each of the wells. You are looking for what is called
agglutination to occur. Agglutination is what is happening if the blood appears to be clumping (be
aware that this is NOT the same as clotting). If the blood in a well agglutinates that means the blood
contains whatever surface antigen you were testing. For example, if there is agglutination in well “B”,
then the blood contains the B antigen. If agglutination occurs in the well “Rh”, then the blood is
considered to be Rh positive.
Step 4: Make a data table in the “Data” section to record your results. Be sure to include all of the
different blood samples as well as the different blood types in your table. If the well you are testing is
positive for the antigen, mark “+” in your table for that column and if it is negative, mark “-“. An
example for one suspect is shown below. Fill in the blood type for this example.
Name
A
B
Rh
Blood Type
Suspect 1
+
-
+
_______
Step 5: Repeat steps 1-4 for the blood found at the crime scene as well as the blood of each suspect.
Good Luck!!!
Ms. Buchalski
Honors Biology
Data and Observations:
4
Ms. Buchalski
Honors Biology
5
Questions:
1. Who committed the crime? How do you know? Explain.
2. If two of the suspects had the same blood type would you be able to figure out which one did it
using this test? If not, what else could you do to figure out who the killer was?
3. If you already knew a suspect’s blood type was AB- but there was agglutination in the Rh well,
what might you conclude?
4. What blood type are you? (If you don’t know you may choose any blood type). With this blood
type, what blood types would you be able to receive? Who would you be able to donate blood
to?