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Blood genetics

Page history last edited by Sean Haggerty 12 years, 12 months ago

Following Information is false.  Dont listen






Closed & totaled. 1/26/10  Mr F               



Unlike most human traits, blood type is determined by three, not two alleles. The alleles for human blood type inculde O (recessive), and A and B, which are codominant. There are four possible phenotypes for human blood type: A, B, AB, and O. There are six possible genotypes: AA, AO, BB, BO, OO, AB.

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This is a very helpful video that talks about the multiple alleles that determine blood type.



This chart shows the percentages of blood types in the United States. The majority of people have a O blood type or A blood type, while type AB is the rarest. The chart also tells how transfusions work for each blood type.




              A blood test is used to determine whether the A and/or B characteristics are present in a blood sample. It is not possible to determine the exact genotype from a blood test result of either type A or type B.

If someone has blood type A, they must have at least one copy of the A allele, but they could have two copies. Their genotype is either AA or AO. Similarly, someone who is blood type B could have a genotype of either BB or BO.
Blood type Possible genotypes
A blood test of either type AB or type O is more informative. Someone with blood type AB must have both the A and B alleles. The genotype must be AB. Someone with blood type O has neither the A nor the B allele. The genotype must be OO.
Blood type Possible genotypes


An antigen, originally defined as any molecule that binds specifically to an antibody, the term now also refers to any molecule or molecular fragment that can be bound by a major histocompatibility complex (MHC) and presented to a T-cell receptor. "Self" antigens are usually tolerated by the immune system; whereas "Non-self" antigens are identified as intruders and attacked by the immune system. Autoimmune disorders arise from the immune system reacting to its own antigens


An antibody is a type of protein. The body's immune system produces antibodies when it detects harmful substances, called antigens. Examples of antigens include microorganisms (such as as bacteria, fungi, parasites, and viruses) and chemicals.

Antibodies are also be produced when the immune system mistakenly considers healthy tissue a harmful substance. See: Autoimmune disorders

Each type of antibody is unique and defends the body against one specific type of antigen.


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Here is an interesting video that explains all of the genotypes for blood.



Here is the chart which we saw in class. It shows the different blood types and the corresponding antigens and antibodies.


People with Blood Type O have the advantage when it comes to donating blood because they can donate to any other blood type.  The blood cells do not have any antigens, and so there will be nothing for the antibodies to attack, however Type O can only receive from other Type O's because it's anti-A and anti-B will attack any other blood type.  Type AB is the universal receiver.  It does not have any antibodies present because it has both A and B antigens, therefore a person with Type AB blood can receive from other Type AB's as well as Type A, Type B's, and Type O's.




This animation provides an interesting example on how to test for blood types and how it relates to the different antigens in different blood types. It shows how transfusing different blood types can sometimes lead to clotting which can be fatal.




The link above is to a video which is very helpful for understanding blood types and it incorporates how these blood types are important for blood transfusions.


Here is an informative video on Blood genetics.

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Here's a link that's very helpful in understanding blood genetics, it goes into depth with blood type crosses and provides good example of how one may end up with a certain blood type: http://www.biology.arizona.edu/human_bio/problem_sets/blood_types/Intro.html


Want to make Bio more fun? Here is a game I found on the Nobel Peace Prize website about blood typing. Have fun with bio! http://nobelprize.org/educational_games/medicine/landsteiner/



here is a good grphic that explains in detail that two different parent with codominant blood types can have four different blood typed children:


here is the same type of picture as the one above, though this one explains the sex-linked genes, and the offspring possible:


This picture is an example of a more advanced Punnett square. 


The following link helps the understanding of how common certain blood types are, specifically in the United States.



Here's a brilliant link that is a great help in understanding blood types and how they compare to each other: http://learn.genetics.utah.edu/content/begin/traits/blood/ 

^This is a very easy understanding of how and what blood genetics is and how it works. 

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