Human Blood Groups- Multiple Alleles AND CoDominance

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Human Blood Groups- Multiple Alleles AND
CoDominance
OK Humans and many other primates
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• 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

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Allele from Parent 1 Allele from Parent 2 Genotype ofoffspring Blood types ofoffspring (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
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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.

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• Therefore, each person can have antibodies
  against an antigen they didnt inherit.
• These antibodies are floating around in our
  blood with our RBCs.

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• 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

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• Type AB blood doesnt have any antibodies
• Type O blood has Anti-A and Anti-B antibodies

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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).

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• 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 dont

Mother Father Child
Rh- Rh Rh
Rh- Rh- Rh-
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The Rh Issue Mom Rh- Baby 1 Rh