Blood Lab

Target audience 9-12

Background:

The ABO System of Blood Typing:

A, B, and Rh factors in blood are important in forensic serology because it can be done quickly and relatively inexpensively. Identification of blood type can indicate the identity of a suspect or victim. Then further, more expensive tests, e.g. DNA fingerprinting, can be done to confirm the identify of the person. About 80% of the population is secretors which means that their blood type antigens are found in body fluids other than blood: therefore other fluids can also be used in identification.

Blood cells are covered with polysaccharides known as antigens which react with antibodies found in blood serum (plasma) causing blood cells to coagulate in an agglutination reaction like a chemical precipitation reaction. There are 2 basic antigens: A and B. There exist antibodies to the two antigens, A & B. A person’s Red Blood Cells can have either, both or none of these antigens resulting in a variety of blood types (e.g. A, B, AB, or O blood types). The purpose of the antibodies in the blood serum is to attack invaders that enter the blood system, e.g. viruses or bacteria. Thus, a type A person produces anti-B antibodies or anti-B serum that destroys type B blood cells and vice versa. Type O has both anti-A and anti-B antibodies in its serum while type AB has neither type A or B antigens on the surface of its blood cells. Using the wrong blood type can be fatal in blood transfusions and organ transplants as in the case of Jessica Santillan at Duke Hospital. Rh factor is sometimes referred to as the D antigen. Rh+ people have the factor and Rh- do not. About 85% of the general population has the Rh factor. Generally 41% of a population are type A, 10% type B, 4 % type AB and 45% type O. Type O is a universal donor, which is a relatively rare blood type. Type AB is a universal receiver.

Examples of blood type testing:

Agglutination i.e. a reaction between antigen and antibody which causes clumping of the blood cells, occurs where there is a + sign in the table in this lab activity.

Blood Group

/

Antigens

/

Antibodies

/

Can give blood to

/

Can receive

blood from

AB / A and B / None / AB / AB, A, B, O
A / A / B / A and AB / A and O
B / B / A / B and AB / B and O
O / none / A and B / A, B, AB, and O / O
Blood tested with Rh factor antibody
Rh+ / +
Rh- / -

Knowledge and skills

  • Students should know the basic blood and cell biology.

Fundamental Understanding:

  • Understand the use of blood typing in forensic science.
  • Understand the antibody antigen interactions

Essential Question

  • How can blood evidence be used in forensic science.

Materials:

ABO/Rh Simulated Blood Typing Laboratory Kit, Flinn Scientific Catalog # FB1225.

Resources and references;

  1. ABO/Rh Simulated Blood Typing Laboratory Kit, Flinn Scientific Catalog # FB1225.
  2. Saperstein, Richard, “Criminalistics: An Introduction to Forensic Science”, Prentice Hall, Inc., Upper Saddle, NJ 07458, 2001. ISBN 0-13-013827-4 (textbook with lots of background information and figures)
  3. Walker, Pam and Wood, Elaine; “Crime Scene Investigations – Real Life Science Labs for Grades 6-12”, Prentice Hall (Simon and Schuster) by The Center for Applied Research in Education, West Nyack, NY 10994, 1998. ISBN 0-87628-135-8 ( (good simple lab activities to start basic Forensic units for many grade levels)

Website:

Teacher Notes:

This kit is teacher friendly, very easy to use and with worksheets that are clear and understandable. See student notes on blood for more information.

Optional Lab: Blood Alcohol Determination Lab from Carolina Biological Supply (Kit # ER-69-9772

Results for the tests were:

Person W was AB+

Person X was O-

Person Y was A+

Person Z was B-