I don't understand the blood types.?

Question

What different between A, AB, O and B?

Answer 1

The different blood types are dependent on sugar based side chains attached to the red blood cell - these are inherited genetically. The sugar group have actually chemical names, but are commonly denoted at A and B antigens. A type A individual has the A antigen. A type B individual has the B antigen and an AB individual has both A and B antigens attached to their RBC's. I like to think of a type O individual as standing for ZERO - meaning they have zero (neither A or B antigens) present on their cells.

Answer 2

The actual difference in the blood is what proteins they have on their red blood cells. Type A blood has some proteins called "A antigens" on the outside of the red blood cells. Type B has "B antigens". Type AB has both A and B antigens. Type O blood has neither A nor B antigens.

Why is it important?
The body "fights off" anything that it sees as being foreign. B antigens are foreign to Type A and Type O blood, but not to Type B or Type AB because those two types have the B antigens and they are not foreign. A antigens are foreign to Type B and Type O blood. Type O blood is the universal donor because it has nothing that would be seen as foreign.
Type AB can accept any kind of blood transfusion because nothing will seem foreign.

What are the alleles for the four blood types?
Type A could be: IA IA or IA i (AA or AO)
Type B could be: IB IB or IB i (BB or BO)
Type AB can only be: IA IB (AB)
Type O can only be: ii (OO)

Notice that A and B are codominant -- they both show up when an individual has both the A and B alleles.
Also, A and B are both dominant to O. That's why we use the i to indicate the O allele.

Answer 3

A blood type (also called a blood group) is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrates, glycoproteins or glycolipids, depending on the blood group system, and some of these antigens are also present on the surface of other types of cells of various tissues. Several of these red blood cell surface antigens, that stem from one allele (or very closely linked genes), collectively form a blood group system.

The ABO blood group system and the Rhesus blood group system are more likely to cause harmful immunological reactions than the other blood group systems. In the routine blood transfusion work of a blood bank, the presence or absence of the three most significant blood group antigens, the A antigen, the B antigen and the RhD antigen (also known as the Rhesus factor or Rhesus D antigen), is determined. This gives the ABO blood group and the RhD antigen status, which are reflected in the common terminology A positive, O negative, etc. with the capital letters (A, B or O) referring to the ABO blood group, and positive or negative referring to the presence or absence of the RhD antigen of the Rhesus blood group system. In the routine preparation and selection of donor blood for blood transfusion, it is not necessary to determine the status of any more blood groups (or antigens), because antibody screening and cross-matching prior to transfusion, detects if there are any other blood group incompatibilities between potential donor blood and intended recipients.

If an individual is exposed to a blood group antigen that is not recognised as self, the immune system will produce antibodies that can specifically bind to that particular blood group antigen and an immunological memory against that antigen is formed. The individual will have become sensitized to that blood group antigen. These antibodies can bind to antigens on the surface of transfused red blood cells (or other tissue cells) often leading to destruction of the cells by recruitment of other components of the immune system. It is vital that compatible blood is selected for transfusion and that compatible tissue is selected for organ transplantation. Transfusion reactions involving minor antigens or weak antibodies may lead to minor problems. However, more serious incompatibilities can lead to a more vigorous immune response with massive RBC destruction, low blood pressure, and even death.

Blood types are inherited and represent contributions from both parents. Often, pregnant women carry a fetus with a different blood type from their own, and sometimes the mother forms antibodies against the red blood cells of the fetus, which causes hemolysis of fetal RBCs, and which in turn can lead to low fetal blood counts, a condition known as hemolytic disease of the newborn. Some blood types are associated with inheritance of other diseases; for example, the Kell antigen is associated with McLeod syndrome.[1] Certain blood types may affect susceptibility to infections, an example being the resistance to specific malaria species seen in individuals lacking the Duffy antigen.[2]The Duffy antigen, as a result of natural selection, is less common in ethnic groups from areas with a high incidence of malaria.[3]

The two most significant blood group systems were discovered during early experiments with blood transfusion: the ABO group in 1901[4] and the Rhesus group in 1937.[5] Development of the Coombs test in 1945,[6] the advent of transfusion medicine, and the understanding of hemolytic disease of the newborn led to discovery of more blood groups. Today, a total of 29 human blood group systems are recognized by the International Society of Blood Transfusion (ISBT).[7] A complete blood type would describe a full set of 29 substances on the surface of RBCs, and an individual's blood type is one of the many possible combinations of blood group antigens. Across the 29 blood groups, over 600 different blood group antigens have been found,[8] but many of these are very rare or are mainly found in certain ethnic groups. Almost always, an individual has the same blood group for life; but very rarely, an individual's blood type changes through addition or suppression of an antigen in infection, malignancy or autoimmune disease.[9] Blood types have been used in forensic science and in paternity testing, but both of these uses are being replaced by DNA analysis, which provides greater certitude.

Answer 4

the antigens