12 January 2015
What do you know about blood types?
What causes differences in blood types?
What use do you think they might have for
forensics?
What questions do you have?

Blood factors are proteins found in blood that differ between
individuals

More than 250 different blood factors!

Some blood factors are also antigens – substances that are capable
of causing an immune response in people who don’t have them

The blood factors that cause the greatest immune response belong
to the ABO and Rh groups.
 Antigens are foreign substances that provoke an immune response –
usually the release of antibodies that bind to and attack them

Where are they found?
 Surface of pathogens (e.g. viruses, bacteria, etc.)
 Vaccines (that’s why they work!)
 Allergens (e.g. pollen, dust, etc.)
 Cancer cells (foreign b/c cell has mutated)
 Transplanted tissue / organs

Antibodies are proteins produced by white blood cells that bind to and
destroy antigens. Antibodies are specific to certain antigens

When antibodies bind to
RBCs, they cause
agglutination, or clumping
Why is this bad?

Initially, clumps clog small
capillaries, causing pain and
reduced blood flow

Later, RBCs that are bound to
the antibodies lyse or break
open, releasing hemoglobin
into the blood – which can
cause kidney failure

In the ABO blood group, there are two antigens, “A” and “B”,
found on the surface of RBCs
 You can have
one type of
antigen, both
types, or
neither
 You develop
antibodies to
the type of
antigens you
don’t have
during infancy
Determine whether each statement is correct as written. If it is not
correct, re-write it.

The “A” and “B” antigens are examples of blood factors. Correct!

If you have type “B” blood then you have “B” antigens. “A” antigens

If you have type “AB” blood then you have “O” antibodies. Do not have “A” or
“B” antibodies
antigen

For people who have allergies, pollen is an antibody.

Agglutination occurs when antibodies bind to the antigens in Correct!
blood.

Antibodies are found on the surface of red blood cells. In the blood plasma
The key to transfusions:
You cannot give a person blood that has antigens for which
they have antibodies, otherwise, their immune system will
attack that blood.
Fill out the chart …
Blood Can donate to
Type
A
B
AB
O
Which type is the universal donor?
Can receive from
Which type is the universal recipient?
The key to transfusions:
You cannot give a person blood that has antigens for which
they have antibodies, otherwise, their immune system will
attack that blood.
Fill out the chart …
Blood
Type
A
B
AB
O
Can donate to
Can receive from
A, AB
B, AB
AB
A, B, AB, O
A, O
B, O
A, B, AB, O
O
Which type is the universal donor? O
Which type is the universal recipient? AB

The Rh blood group describes ~45 different (but similar) antigens on
RBCs. These antigens are called antigen “D”

People are Rh + if they have any of the various D antigens. They are
Rh – if the do not have any D antigens.

Unlike the ABO system, Rh- people must be sensitized to the D
antigen before developing antibodies. That means Rh- people will
NOT have an agglutination reaction the first time they encounter
Rh+ blood … but they will if they have it a second time.
Blood Can donate to
Type
Rh+
Rh-
Can receive from

The Rh blood group describes ~45 different (but similar) antigens on
RBCs. These antigens are called antigen “D”

People are Rh + if they have any of the various D antigens. They are
Rh – if the do not have any D antigens.

Unlike the ABO system, Rh- people must be sensitized to the D
antigen before developing antibodies. That means Rh- people will
NOT have an agglutination reaction the first time they encounter
Rh+ blood … but they will if they have it a second time.
Blood Can donate to
Type
Rh+ Rh+
RhRh-, Rh+
Can receive from
Rh-, Rh+
Rh-

Rh- moms can carry a Rh+ baby if the dad is Rh+

The first baby is usually born without any problems, but during
delivery, some of the baby’s D antigens will contact the mom’s blood,
causing her to be sensitized to D antigens.

If the mom becomes pregnant with a second Rh+ baby, her immune
system will attack the baby’s blood, causing brain damage or death
to the fetus.

This can be prevented by giving the
mother medicine that prevents her from
developing antibodies against D
antigens.
No problems occur if the baby is Rh- and
the mom is Rh+
Antiserum is a solution that
contains antibodies against a
specific antigen (i.e. antiserum A
contains type A antibodies).
Blood type is determined by
adding antiserum A, B, and D to
blood and observing whether or
not agglutination occurs.
Antiserum is a solution that
contains antibodies against a
specific antigen (i.e. antiserum A
contains type A antibodies).
Blood type is determined by
adding antiserum A, B, and D to
blood and observing whether or
not agglutination occurs.
Front two rows…
On the front of a notecard / scrap paper, draw a possible result for a
blood typing test.
On the back, write the correct blood type.
Back rows …
On the front of a notecard / scrap paper , write a question about blood
transfusions.
On the back, write the answer.

To identify people or link suspects to crime scenes

To identify paternity
We have two versions – or alleles – of every gene. One inherited from
our mom, one from our dad.
The two alleles (genotype) interact to determine our trait (phenotype)
in predictable ways.
 Some alleles are dominant, some are recessive. Dominant genes
show their trait and ‘cover up’ recessive genes.
▪ IA (A) and IB (B) are dominant to i (O).
▪ D (+) is dominant to d (–)
 Some alleles are codominant. This means both alleles fully
express their trait.
▪ IA and IB are codominant with each other.
What blood type will result from each genotype?
1.
2.
3.
4.
5.
IAiDD
iidd
IB IB Dd
IA IB dd
IB iDd
What blood type will result from each genotype?
1.
2.
3.
4.
5.
IAiDD
iidd
IB IB Dd
IA IB dd
IB iDd
A+
OB+
ABB+
What are the possible genotypes for each blood type?
1.
2.
3.
4.
A+
ABOB+
What are the possible genotypes for each blood type?
1.
2.
3.
4.
A+
ABOB+
IAIADD, IAiDD, IAIADd, IAiDd
IAIBdd
iidd
IBIBDD, IBiDD, IBIBDd, IBiDd
Other important vocab –
Homozygous – both alleles for one gene are the same (e.g. ii)
Heterozygous – the two alleles for one gene are different (e.g. Iai)
Punnett Squares are a tool for predicting the traits that will result
from crossing certain genotypes.
We do ….
1.
Iai X ii
2. IBIB X Iai
You do …
3. Dd X dd
4. IAIB X ii
We do …
1. IAiDd X iiDd
2. AB- X iiDD
You do …
3. IBiDd X IAiDD
4. IAidd X IBiDd
Closure –
Unit question? Something new? LP? TOK?
Exit Ticket –
Pick a blood type. For that type, list
 Antibodies
 Antigens
 Blood typing test results
 To whom can it donate?
 From whom can it receive?
 Genotype
Homework–
Homework sheet due next class. Major quiz in two classes.