Genetics of blood typing

Blood Typing and Blood

Genetics

Blood Genetics

● The human ABO gene is on chromosome 9.

● Everyone has two copies of chromosome 9

so you have two ABO genes.

● One copy is inherited from our mother, the

other from our father.

Multiple Choice

What is the human ABO blood types?

• A, B, C, D

• A, B, AB, O

• A, B, C, O

• AB, O

Alleles

● There are three versions (called “alleles”) of

this blood type gene: A, B, and O.

● A person’s blood type is determined by

which allele he/she inherits from each
parent.

Pheno vs. Geno

● The genetic makeup of an organism is

called the “genotype”.

● The “phenotype” is the visible properties of

an organism.

● In this case, the A, B, and O allele

combination a person has is their genotype

● Their blood type is their phenotype.

Dominant vs. Recessive Genes

● The “A” allele is dominant and so is the “B”

allele.

● Together though, the “A” and “B” alleles are

co-dominant.

● The “O” allele is recessive.

Determining the Genotype

The blood type gene has three different

alleles:

● IAIAis Type A

● IAIB is Type AB

● IBIB results in Type B

● ii is Type O

Determining the Genotype

● Scenario:

● Mom has the alleles IAIA for blood type and Dad

has the alleles IBIB blood type.

● What will be the blood type for their child?

Punnett Sqaures

IB

IB

IA

IA

Practice

Suppose that a mother has blood Type A
and genotype IAi and the father has blood
Type B and genotype IBi. Draw a Punnett
square to show the possible genotypes of
their children.

What are the phenotypes of the kids?

Practice

i

IA

i

IB

Blood Types

● The alleles we discussed “code” for blood

type.

● What they REALLY “code” for is a specific

enzyme.

● That enzyme creates specific antigens on

your RBC.

Antigens

● An antigen is a protein (encoded from the

right enzyme) that “sits” on the surface of
your RBC.

● There are 2 different blood antigens, A and

B.

● If you have the A antigen, you have type A

blood.

● If you have the B antigen, you have type B

blood.

Antigens of the Surface of the RBC

Antibodies

● Blood plasma is packed with proteins called

antibodies.

● The body produces a wide variety of

antibodies that will recognize and attack
foreign molecules.

● A person’s plasma does not contain any

antibodies that will bind to molecules that
are part of his or her own body.

Blood Transfusions

● Tt is important to carefully match the donor

and recipient blood types.

● If the donor’s blood cells have antigen that

are different from those of the recipient,
antibodies in the recipient’s blood recognize
the donor blood as foreign.

● This triggers an immune response resulting

in blood clotting.

Blood Transfusions

O

AB

B

A

Can receive

from…

Can donate

to…

Antibody

Antigen

Relative Abundance of Blood Types

43-45%

3-5%

10-12%

40-42%

O

AB

B

A

Interesting Facts

● Men generally have more red blood cells

than women.

● Rare blood types exist in addition to the

basic ABO system.

Rhesus Factor (Rh)

● If a person has a positive Rh factor, this

means that their blood contains a protein
that is also found in Rhesus monkeys.

● Most people (about 85%) have a positive Rh

factor

● Rh is expressed as either positive or

negative.

● The Rh factor, like other antigens, is found

on the surface of the red blood cells.

Stats

1 in 167 persons

AB-

1 in 29 persons

AB+

1 in 67 persons

B-

1 in 12 persons

B+

1 in 16 persons

A-

1 in 3 persons

A+

1 in 15 persons

O-

1 in 3 persons

O+

Can Blood Be Individualized?

● Is based on the typing of proteins and

enzymes. Blood proteins have subtypes.

● Most people are familiar with at least one

common polymorphism in blood: Hb, which
causes sickle-cell anemia.

● You can also extract DNA from it.

Multiple Choice

Which of the following are genotypes for blood type B?

• I^A I^A and I^A I^B

• I^B I^B and ii

• I^B I^B and I^B i

• I^A I^B and I^A I^B

Multiple Choice

In the image above, what is the percentage of the offspring has the possibility of inheriting blood type O?

• 0%

• 25%

• 50%

• 100%

Multiple Choice

Which of the following genotypes code for the blood type AB?

• I^A I^A and I^A I^B

• I^A I^B only

• I^A I^B and I^B i

• ii only

Multiple Choice

Which of the following codes for blood type O?

• I^A I^A

• I^B i

• I^A I^B

• ii

Multiple Choice

If two parents have type AB blood, what is the probability that their child will have type O blood?

• 0%

• 25%

• 50%

• 100%

Multiple Choice

If two parents are heterozygous for type A blood, what is the probability that their offspring would have type O blood?

• 100 %

• 75%

• 50%

• 25%

Multiple Choice

What are the blood types of the possible children that a woman (type O) and man (type AB) can have?

• O and AB

• O and A

• O and B

• A and B

Multiple Choice

What is produced by your body in response to foreign antigens, such as the wrong type of blood?

• agglutinates

• clotting factors

• phagocytes

• antibodies

Multiple Choice

Which of the following is true about blood type O?

• It contains antigen A only.

• It contains antigen B only.

• It contains both antigen A and antigen B.

• It doesn’t contain antigen A or antigen B.

Multiple Choice

Which blood type is the universal recipient?

• AB+ 

• AB-

• O+

• O-

Multiple Choice

It is the universal blood donor.

• Blood Type A

• Blood Type B

• Blood Type AB

• Blood Type O

Multiple Choice

Any pattern of inheritance in which traits do not segregate in accordance with Mendel's Laws.

• Mendelian Inheritance

• Non - Mendelian Inheritance

• Punnett Square

• Chromosomes

Multiple Choice

What are the 4 Types of Blood?

• Types A,B,C and D

• Types A,B,O and D

• Types A,B,AB and O

• Types A,E,O,U