human blood groups- multiple alleles and codominance ok… humans and many other primates
TRANSCRIPT
Human Blood Groups-
Multiple Alleles AND CoDominance
OK… Humans and many other primates
Recall: There are three different alleles for human blood type (multiple alleles):
Alleles Blood Type
IA A
IB B
i O
•“A” indicates the presence of 1 type of antigen (protein that can “activate” your immune system) and “B” represents a different antigen on the surface of a red blood cell
•“O” has no antigen on the surface of the RBC
Allele from Parent 1
Allele from Parent 2
Genotype ofoffspring
Blood types of
offspring (Phenotype)
A A AA A
A O AO A
B B BB B
B O BO B
A B AB AB
O O OO O
Antibodies• A “foreign” antigen will trigger your immune system
to create antibodies.• Since antibodies are proteins, they have a specific
shape & will attach onto the antigen for which they were made.
• There are bacteria in the atmosphere that have a very similar shape to our “A” and “B” antigens & we are exposed to them as soon as we are born.
• Therefore, each person can have antibodies against an antigen they didn’t inherit.
• These antibodies are floating around in our blood with our RBC’s.
• Type A blood (has A antigens on cell surface) has Anti-B antibodies – Antibodies are named for
what they attack– Anti-B antibodies attack and
will clump up (agglutinate) in the presence of B-antigen
• Type B blood (has B antigens on cell surface) has A-antibodies
• Type AB blood doesn’t have any antibodies
• Type O blood has Anti-A and Anti-B antibodies
Rh Factor• The Rh factor genetic information is also
inherited from our parents, but it is inherited independently of the ABO blood type alleles (a separate gene).
Mother Father Child
Rh- Rh+ Rh+
Rh- Rh- Rh-
•There are 2 different alleles for the Rh factor known as Rh+ and Rh-.
•Normal dominant/recessive inheritance
•Positive (+) allele is dominant to negative (-) allele
•Rh +: you have the protein Rh-: you don’t
The “Rh Issue”… Mom = Rh- Baby #1 = Rh+