NAME ______Pd ______Date ______

Switched At Birth? A Blood Typing Lab

Background: Two couples were in the delivery room of St. Barnabas Hospital delivering their babies during Hurricane Sandy. Both babies were born at the same time as the electricity went out and somehow, in the confusion, the babies may have gotten switched. Now, the parents want to know which baby is theirs.

For the sake of protecting their identities, we’ll call the families the Smiths and the Jones. Mr. and Mrs. Smith and Mr. and Mrs. Jones have agreed to submit to blood testing to identify which of the two babies, Child 1 and Child 2, is actually their own.

St. Barnabas has asked us to help identify which baby is which. They have sent us blood samples of all 4 parents and both babies.

Information you need to know:

While the test procedures used in this lab are those used to test real blood, we will not be using real blood to eliminate any risk associated with exposure to actual blood or blood products. Some people have proteins on the outside of their blood cells, while other people do not. People without proteins on their blood cells have blood type O. People with A proteins have blood type A, and people with B proteins have blood type B. Some people have both A and B proteins. Their blood type is called blood type AB.

If a person receives blood with a protein that they do not have in their own blood, then they will produce antibodies to attack the foreign blood and cause it to clot. This can be very dangerous. For example, if a person with blood type A (has A proteins on his blood cells) receives blood with B proteins, then he will produce antibodies against B (anti-B proteins) and kill the B blood cells. A person with O type blood has no A or B proteins on their blood, so they will produce antibodies against either A or B blood. A person with AB blood will not produce antibodies against either A or B because he has both proteins in his blood already. This is summarized in the following chart on the next page:

Peron’s blood type / Can receive blood of this type: / Cannot receive blood of this type:
A / A, O / B, AB
B / B, O / A, AB
AB / A, B, AB, O
O / O / A, B, AB

ABO blood typing is inherited by multiple alleles. There are two dominant alleles, A and B. A and B are co-dominant, which means that they are equally dominant if they are both found in the same person. There is one recessive allele, O. A person can have any two of those three alleles. If a person has the genotypes AA or AO, their blood type is type A. If a person has the genotypes BB or BO, their blood type is type B. If a person has the genotypes AB, then their blood type is AB. A person with the genotype OO has blood type O. This is summarized in the following table:

Genotype / Phenotype
AA / A
AO / A
BO / B
BB / B
AB / AB
OO / O

Name:______Period:______

Materials:

·  Blood samples of Mr. Smith, Mrs. Smith, Mr. Jones, Mrs. Jones, Child 1, and Child 2

·  Anti-A and Anti-B serums

·  Blood typing slides, toothpicks

Procedure:

1.  Place 6 blood typing plates on a piece of paper.

2.  Label the paper to identify which blood typing plate will represent which person.

3.  Using the dropper vial, place 2-3 drops of Mr. Smith’s blood in two wells of the

blood typing slide. We won’t be testing for Rh, so don’t place any blood in the Rh well.

4.  Replace the cap on the dropper. Always replace the cap on one vial before opening the

next vial to prevent cross contamination.

5.  Add a drop of anti-A to the well labeled A. Replace the cap. Anti-A will cause bloods with A proteins to agglutinate (clot).

6.  Add a drop of anti-B to the well labeled B. Replace the cap. Anti-B will cause bloods with B proteins to agglutinate.

7.  Use a toothpick to gently stir the synthetic blood and anti-serum drops for 30 seconds. Use a different toothpick to stir each well!

8.  Discard each toothpick after a single use to avoid contamination.

9.  Carefully examine the thin films of liquid mixture left behind. Pick up the slide and see if the liquid has turned to gel. Look for any signs of small dots that might indicate clotting. If the liquid has turned to a gel or if there are small dots, then agglutination or clotting has occurred. If the liquid is still a liquid and there are no signs of small dots, then agglutination or clotting has not occurred.

10.  Record your results in the data table (write yes if agglutination occurs, no if agglutination does not occur).

11.  Determine the blood type of the sample using the table below. Record your results in the data table.

Blood type / Anti-A / Anti-B
A / Yes / No
B / No / Yes
AB / Yes / Yes
O / No / No

12.  Thoroughly rinse the blood typing slide.

13.  Repeat for the remaining blood samples.

14.  Determine the possible genotypes by using the Information you need to know section of this packet.

Data Table: (10 points)

Blood Sample / Anti-A
(yes or no) / Anti-B
(yes or no) / Blood type / Possible Genotypes
Mr. Smith
Mrs. Smith
Mr. Jones
Mrs. Jones
Child 1
Child 2

Analysis Questions: (2 points each)

1.  Could Child 1 have been born to Mr and Mrs Smith? Why or why not? Use Punnet Squares to explain if needed.

2.  Could Child 2 have been born to Mr and Mrs Smith? Why or why not? Use Punnet Squares to explain if needed.

3.  Could Child 1 have been born to Mr and Mrs Jones? Why or why not? Use Punnet Squares to explain if needed.

4.  Could Child 2 have been born to Mr and Mrs Jones? Why or why not? Use Punnet Squares to explain if needed.

5.  As determined above, the child belonging to Mr and Mrs Smith has blood type B. Does this mean that all children born to Mr and Mrs Smith will have blood type B?

6.  Two parents, genotypes AB and BO produce a child. Determine what the probability is that the child may display each of the 4 ABO blood types. Use a Punnett square and show the results

Type A:______%

Type B______%

Type AB_____%

Type O______%

7.  You are a lawyer representing a man ( Mr Young) with blood type B. A woman with blood type O has a child with blood type A and is proposing that Mr Young is the father of this baby. Use what you have learned about blood typing and genetics and briefly state your argument to the jury in defense of your client.

8.  One blood type is sometimes referred to as the “Universal Donor” because this blood type can be received by every other blood type. Which blood type is it and why?

9.  Another blood type is sometimes referred to as the “Universal Recipient” because this blood type can receive blood from every other blood type. Which blood type is it and why?

10.  Draw a Punnett square showing the possible offspring of a person with the genotype AO and a person with the genotype BO.

Conclusion: (20 pts)

Type a 2-3 paragraph conclusion to this lab. In your conclusion, answer these questions:

·  Were the results of this experiment what you expected? How?

·  In what parts of the experiment might there have been some errors?

·  What did you learn by completing this lab? Don’t just say you learned about blood types – tell me WHAT you learned ABOUT blood types and what you did in the lab to learn it. How are blood types determined in a lab? How are blood types inherited? How did you determine which parent could have which child?

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