Simulated Blood Typing Activity

 

GRADES : 6-12

 

TIME NEEDED: 1 hour

 

Around 1900 it was discovered that there are at least 4 different kinds of human blood. This is based on the fact that on the surface of the red blood cells there may be one or more proteins, called antigens. These antigens are called A and B. Antibodies are produced in the blood plasma against these A and B antigens, and continue to be produced throughout a person's life.

 

A person normally produces antibodies against the antigens that are not present on his or her red blood cells. For example, a person with antigen A on his red blood cells will produce anti-B antibodies; a person with antigen B will produce anti-A antibodies; a person with neither A or B antigens will produce both anti-A and anti-B antibodies; and, a person with both antigens A and B will not produce these antibodies.

 

The 4 blood types are known as A, B, AB and O. Blood type O (persons with neither A or B antigens) is the most common in the United States (45% of the population). Type A is found in 39% of the population. Type B is 12% of the population, and type AB is found in only 4% of the population.

 

Because of the different blood types, certain blood groups can only give or receive blood from other specific blood groups:

 

Blood Type Antigens on Antibodies Can Give Can Receive

Blood Cells in Plasma Blood to Blood from

A A anti-B A or AB O or A

B B anti-A B or AB O or B

AB A and B none AB O, A, B, AB

O none anti-A &-B O,A,B, AB O

 

If blood cells are mixed with antibodies the cells will clump together. This is called agglutination. This is why it can be very dangerous if you receive the wrong blood type in a transfusion.

 

Blood typing is performed by mixing a small sample of blood with anti-A or anti-B antibodies (called antiserum), and the presence or absence of clumping is determined for each type of antiserum used. If clumping occurs with only anti-A serum, then the blood type is A. If clumping occurs only with anti-B serum, then the blood type is B. Clumping with both antiserums indicates that the blood type is AB. No clumping with either serum indicates that you have blood type O.

 

Anti-A Serum Anti-B serum Blood Type

Reaction Reaction of Person

Clumps No Clumps Type A

No Clumps Clumps Type B

Clumps Clumps Type AB

No Clumps No Clumps Type O

 

A person's blood type is inherited from their parents, just like any other genetic trait. Persons with blood type A have inherited one or two copies of the gene for the A antigen, one from each parent. Persons with blood type B have inherited one or two copies of the gene for the B antigen. Persons with blood type AB have inherited on copy of the A antigen from one parent and one copy of the B antigen gene from the other parent. Persons with blood type O inherited neither A nor B genes from their parents.

 

Blood typing can be used in legal situations involving identification or disputed paternity. In paternity cases a comparison of the blood types of mother, child, and alleged father may be used to exclude a man as the possible parent of a child. For example, a child with the blood type AB whose mother is type A could not have a father whose blood type is A or O.

 

The father must have blood type B.

 

NOTE: We are using simulated blood for this activity.

 

Materials Needed per team of 2 students (use Ward's simulated blood typing kit)

 

4 blood typing slides

8 toothpicks

4 unknown "blood" samples (Mr. Smith, Ms. Jones, Mr. Green, Ms. Brown)

anti-A and anti-B antiserums

Procedure:

  1. Label each of your 4 slides as follows:

slide #1: Mr. Smith

slide #2: Ms. Jones

slide #3: Mr. Green

slide #4: Ms. Brown

  1. Place 3 drops of Mr. Smith's blood in the A and B wells of Slide #1.
  1. Place 3 drops of Ms. Jones's blood in the A and B wells of Slide #2.
  1. Place 3 drops of Mr. Green's blood in the A and B wells of Slide #3.
  1. Place 3 drops of Ms. Brown's blood in the A and B wells of Slide #4.
  1. Add 3 drops of the anti-A serum to each A well of the four slides.
  1. Add 3 drops of the anti-B serum to each B well of the four slides.
  1. Use different toothpicks to stir each sample of serum and blood together. Do the cells in any of the wells clump or not? Record your observations and results in the table below. What are the blood types of each of the 4 samples?

Observations

 

Anti-A Serum Anti-B Serum Blood Type

Slide #1: Mr. Smith

Slide #2: Ms. Jones

Slide #3: Mr. Green

Slide #4: Ms. Brown