Blood Typing

Topics: Blood type, Blood, ABO blood group system Pages: 5 (1457 words) Published: March 19, 2012

The purpose of this lab is to determine the blood type of two samples. The objectives of the blood typing lab were to learn about antigens and the consequences of incompatibility, blood typing, and to illustrate antigen-antibody complexes and agglutination.

Red blood cells have glycoproteins on their surface which act like "flags" to identify the cells. The glycoproteins are coded for by the blood type genes A, B, and O. Unlike Complete Dominance where one gene totally masks another (i.E. vs. t), the blood type genes, A and B, are Co-dominant or equally dominant. Therefore, an individual with the genotype AB will possess both A-type glycoproteins and B-type glycoproteins on their RBC's. Antibodies are proteins made by the immune system which attack foreign matter in the body. If A-type blood enters the body, anti-A antibodies will attack it. If B-type blood enters, anti-B antibodies will attack it. If AB- type blood enters, anti-A and anti-B antibodies will attack it. If O-type blood enters, no antibodies will attack since O-type blood cells do not have the glycoproteins on the surface. The presence or absence of the different antibodies determines which blood types can be safely received during a blood transfusion. When antibodies attack blood cells they cause the cells to "clump" or "agglutinate". This agglutination can be used as a clinical test to determine what blood type a person has.

ABO blood group system
ABO blood group system: diagram showing the carbohydrate chains that determine the ABO blood group The ABO system is the most important blood-group system in human-blood transfusion. The associated anti-A and anti-B antibodies are usually immunoglobulin M, abbreviated IgM, antibodies. ABO IgM antibodies are produced in the first years of life by sensitization to environmental substances such as food, bacteria, and viruses. The O in ABO is often called 0 (zero, or null) in other languages. |Phenotype |Genotype |

|A |AA or AO |
|B |BB or BO |
|AB |AB |
|O |OO |

Rh blood group system
The Rh system is the second most significant blood-group system in human-blood transfusion with currently 50 antigens. The most significant Rh antigen is the D antigen, because it is the most likely to provoke an immune system response of the five main Rh antigens. It is common for D-negative individuals not to have any anti-D IgG or IgM antibodies, because anti-D antibodies are not usually produced by sensitization against environmental substances. However, D-negative individuals can produce IgG anti-D antibodies following a sensitizing event: possibly a fetomaternal transfusion of blood from a fetus in pregnancy or occasionally a blood transfusion with D positive RBCs. Rh disease can develop in these cases. Rh negative blood types are much less in proportion of Asian populations (0.3%) than they are in White (15%).[15] In the table below, the presence or absence of the Rh antigens is signified by the + or - sign, so that for example the A- group does not have any of the Rh antigens.

Red blood cell compatibility

Blood group AB individuals have both A and B antigens on the surface of their RBCs, and their blood plasma does not contain any antibodies against either A or B antigen. Therefore, an individual with type AB blood can receive blood from any group (with AB being preferable), but can donate blood only to another type AB individual. Blood group A individuals have the A antigen on the surface of their RBCs, and blood serum containing IgM antibodies against the B antigen. Therefore, a group A individual can receive blood only from individuals of groups A or O (with A being preferable), and can donate blood to individuals with type A or AB. Blood group...

References: (blood typing) (blood typing)
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