Warm-Up
 List one thing you learned from the reading on
Thursday.
Blood Typing
Review of “Forensics of Blood”
 What are the 2 main tests to determine if blood is
present?

Luminol and Kastle-Meyer (phenolphthalein/peroxide)
http://www.youtube.com/watch?v=sF0Z0jJGwX8
 Do both tests work on human and animal blood?
 How do we determine if the blood is human or animal?

Precipitin Test – presence of human blood revealed through
clotting
Review of “Forensics of Blood”
 What are the 2 main tests to determine Blood Type
of a blood sample?

Test for the presence of Antigens or Antibodies
http://da.humanbiologi.wikia.com/wiki/Blodet
Testing for Antigens
 Recall: Antigens exist on the surface of red blood
cells.

Either A or B
Type A – has A antigens
 Type B – has B antigens
 Type AB – has both A and B antigens
 Type O – has neither antigens

http://da.humanbiologi.wikia.com/wiki/Blodet
Blood Clotting
http://www.edu.pe.ca/threeoaks/teacherpages/higginbotham/Biology%20521%20Webpage/resources.htm
Testing for Antigens
 Recall: Antibodies: attach only to foreign antigens
 A antigens produce anti-B antibodies
 B antigens produce anti-A antibodies
Testing for Antigens
 Forensic scientists can inject antibodies to determine
blood type:


Anti-a antibodies only bind to A antigens (forming a clot)
If clotting occurs when anti-a antibodies injected in blood,
then blood is Type A or Type AB
Anti-A
Anti-B
Antigen
Present
Blood Type
+
-
A
A
-
+
B
B
+
+
A&B
AB
-
-
None
O
Testing for Antibodies
 Forensic Scientists inject A or B cells into a blood
sample to identify antibody present

If clotting occurs when A-Cells are injected, then anti-A
antibodies are present and the sample is either Type B or Type
O
Type A Cell
Type B Cell
Antibody
Present
Blood Type
+
-
Anti-A
B
-
+
Anti-B
A
+
+
Both
O
-
-
None
AB
Review ABO Blood Typing Lab
 Which of the two blood typing methods did we use in
the lab? Testing for antigen or antibody?

Support your answer.
 Grades: as long as you typed your blood correctly
based on your results, you received full credit for
data collection.
Blood Mystery Lab
 You will be completing another lab today – this will a
100 pt lab
 You should be able to complete the entire lab in
class, if you use your time wisely.
 You will follow the lab instructions, but will also be
asked several questions throughout the lab
Blood Mystery Lab: Report Requirements
 Background Section
 3-5 sentences explaining blood typing.
 Materials Section
 List all materials used in the lab.
 Results:
 All data tables drawn on a separate sheet of paper.
 Conclusion:
 Separate page for all written answers.
 Complete sentences for all answers.
Groups
1.
2.
3.
4.
5.
6.
7.
8.
9.
Nik, Saul, Alison
Luke, Cynthia, Samantha
Jason, Crystal, Gabby
Darrick, Cesar, Lindsey
Victoria, Hailey, Blake
Brandon, Madi R., Shawn
Alexis, Chris, Jesus
Noe, Katherine, Madi M.
Callan, Aubrey, Marcus
10. Kyle, Kelcey, Gara
11. Nancy, Kayla, Malik
12. Alex, Courtney, Carolina
Background
YOU WILL WORK AS A GROUP TO ANSWER
QUESTIONS ABOUT BLOOD TYPING.
Background Section
 You will have 10 minutes to work with your partners
to draft/write your background section.
 Discuss the following questions:



Why do we use blood typing to solve crimes?
How do we test for blood type?
What are the limitations of blood typing?
 You may discuss the answers to these questions as a
group, but you must all write your own background
section.
Data Collection: Part 1
WE WILL COME BACK TO MATERIALS. SAVE
ROOM IN YOUR LAB REPORT TO LIST YOUR
MATERIALS.
Police Report:
Police are called to a house where they discover a body
near the back door. There is a fresh pool of blood by
the victim's head. Officers question the neighbors and
learn that a plumber and an electrician made service
calls to the house just hours before. They are able to
trace both. They recover a shirt with dark stains from
the service van of the plumber and rags with similar
dark stains from the electrician's van
Samples sent to Lab:
 Your forensics lab receives the following items to
test:



Sample 1: Stained cloth from the plumber's van
Sample 2: Stained cloth from the electrician's van
Sample 3: Blood collected from under the victim's head
Your Task:
 First, test the shirt and rags to determine if the stains
are caused by blood.
 Go to your workstation and place a drop of
phenolphthalein/peroxide solution on each stain.
 A purple-violet color reaction indicates that blood
may be present. The absence of this reaction
indicates that blood is not present. Record your
results.
Conclusion
THE FOLLOWING SLIDE CONTAINS THE
QUESTIONS FOR PART 1. I SUGGEST YOU
START A NEW PAGE TO ANSWER THESE
QUESTIONS.
Part 1 Questions:
 Why do we use the Kastle-Meyer test instead of
Luminol?
 From your lab:

Based on the results of this test, which person, the plumber or
the electrician, becomes your chief suspect?

Support your answer.
 Can you rule out the other suspect? Why or why not?
Data Collection: Part 2
Part 2
 When confronted, your chief suspect claims to have
had a nosebleed, thus accounting for the bloodstain.
investigators have now been able to recover a blood
sample (Sample 4) from the suspect's van. lt is
suitable for blood typing. You ask for and receive a
blood sample from the suspect (Sample 5).
Part 2 Questions:
 Why should we type both suspect 4 and 5?
 Read the instructions in your lab for blood typing.
 Which method of blood typing are we using (finding antigens
or antibodies)? Support your answer.
Part 2: Data Collection
 Follow the instructions in your lab to find the blood
type for each sample.
Results: Part 2
BE SURE TO INCLUDE A DATA TABLE IN
YOUR FINAL REPORT THAT INCLUDES ALL
OF THE DATA COLLECTED DURING THIS
PART OF THE LAB.
Part 2: Recording Data
Conclusion: Part 2
THE FOLLOWING SLIDE HAS THE REMAINING
QUESTIONS FOR THE LAB. THESE SHOULD
BE ADDED TO THE END OF YOUR QUESTIONS
FROM PART 1.
Post Lab Questions:
 Based on your results, did the blood collected from
the suspect's van come from the suspect?

Support your answer.
 Could this blood have come from the victim?
 Support your answer.
 Based on evidence, who is your prime suspect? Did it
change from Part 1? Why or Why not?
 What would be your next step in this investigation?
 Can you rule out either person as a suspect? Why or
why not?
Materials
DRAFT A LIST OF ALL MATERIALS USED IN
THIS LAB.
Closure
 At the end of your lab report answer the following
questions (note - there is no write or wrong answer):



What was the most challenging aspect of the lab?
What did you like about completing the lab this way (with all
of the steps & questions outlined in the PPT)?
What did you dislike about completing the lab this way?