Blood Types & Inheritance
Dr. Charles Drew
• Today's American Red Cross
blood program is the result of
the efforts of Dr. Charles R.
Drew, a blood specialist,
surgeon, educator and scientist.
• His pioneering work in blood
collection, plasma processing
and transfusion laid the
foundation for modern blood
banking.
What are antigens & antibodies?
• The differences in human blood are due to protein
molecules called antigens and antibodies.
• The antigens are located on the surface of the red blood
cells’ plasma membrane.
• The antibodies are in the blood plasma (liquid).
– Antibodies are used to identify/destroy foreign blood
cells.
What are the different blood groups?
• Individuals have different types and
combinations of antigens and antibodies.
What happens when different blood types
are mixed?
• Not all blood groups are compatible with each
other.
• Mixing incompatible blood groups leads to blood
clumping or agglutination, which is dangerous for
individuals.
• This can lead to death
How is blood type genetically
determined?
• The ABO genes are determined by multiple and
co-dominant alleles.
• There are three different alleles for human
blood type: IA ,IB , & I
• Since there are 3 different alleles, there are 6
different possible genotypes and 4 different
possible phenotypes.
Phenotype/
Blood Type
O
A
B
AB
Genotype
Meaning
OO
Neither A nor B
antigens are present
Aa or AO
Only the A antigen is
present
BB or BO
Only the B antigen is
present
AB
A & B antigens are
present
Phenotype/
Blood Type
Genotype
Meaning
ii
Neither A nor B
antigens are present
O
A
IAi
B
IB i
AB
or
IA IA
Only the A antigen is
present
or
IB IB
Only the B antigen is
present
IAIB
A & B antigens are
present
Blood Transfusions - who can receive blood
from whom?
• The transfusion will only work if the
recipient does not produce antibodies
for the donor’s blood type.
Blood
Types
Can donate
blood to
Can receive
blood from
AB
AB
AB, A, B, O
A
A & AB
A&O
B
B & AB
B&O
O
AB, A, B, O
O
• The Universal Donor can donate blood to a
person any blood type.
• Which blood type is the Universal Donor?
O• The Universal Recipient can receive blood
from any blood type.
• Which blood type is the Universal
Recipient? AB+
Population Distribution of Blood Types in the U.S.
Type
Percent
O
45
A
40
B
11
AB
4
Practice Problems!
Give the genotype & phenotype ratios for the
following crosses:
1. IAIA x IBi
Genotypes: 1 IAIB : 1 IAi
Phenotypes: 1 AB : 1 A
2. Type O x Type AB
Genotypes: 1 IAi : 1 IBi
Phenotypes: 1 A : 1 B
Who’s Baby is it?
At the hospital, 2 newborn babies were
accidentally mixed up and the parents
questioned which baby belonged to whom. The
blood groups of everyone involved are listed
below. Determine which baby belongs to which
couple.
Baby 1 – Type A
Baby 2 – Type O
Mr. Brown – Type AB
Mrs. Brown – Type B
Mr. Smith – Type B
Mrs. Smith – Type B
Who’s baby is it? answer…
• Baby 1 has to belong to Mr. & Mrs. Brown.
There is no way that they could create a Type
O (ii) baby when only one parent could
possibly contain the i allele.
• Baby 2 has to belong to Mr. & Mrs. Smith.
There is no way that they could create a Type
A (IA IA, IAi) baby with out either carrying the
IA allele.
Which child is adopted?
• The Tyler family has three kids, one of which
is adopted. The blood types of the parents and
children are listed below. Determine which
child is adopted.
Mom -Type AB
JohnType B
Dad- Type O
Martha- Type AB
Zackary- Type A
Which child is adopted? ANSWER
Martha (IAIB) is adopted because Dad is Type O (ii)
and could not have given either of her two alleles.
Genetics and Biotechnology TEST
Study Guide
• Be familiar with the following terms,
homozygous, heterozygous, phenotype,
genotype, pure bred, and hybrid.
• Know how to solve genetics problems.
• Know the purpose of a test cross.
• Be familiar with the following terms:
selective breeding, genetic engineering,
cloning, DNA fingerprinting.
• Know how to read a karyotype.
• Be able to do sex linkage problems and
blood group problem
• Know how to read a pedigree(we will do
this when I return)