What on the blood determine a person's blood type?
2 Answers
The presence or absence of certain specific antigens - known as A, B, and D (the Rh factor)
Explanation:
The four major blood groups are classified according to the absence or presence of certain protein markers or antigenic markers on the cell membrane.
These antigens (A, B, and D [the Rh factor]) are immunologically reactive, that is, they evoke a strong antibody response, and hence are used to classify the person's blood group.
If you want to know exactly how the genetics work...
Explanation:
A bit of background info on genetics:
Each parent has two genes for most things (Like blood types). Each passes on one to their child. Some genes are dominant over others, which means that if the dominant gene is present, the other gene will be "masked" and will not show in the corresponding trait. (In this case, blood type.) However, "masked" genes can still be passed on.
The "positive" rh gene, when inherited from any parent, will make the child's blood type positive. A negative blood type is simply the lack of the rh gene. The O blood type is a recessive ("masked") trait that will only show in the child's blood type if no A or B genes are present. A and B genes are co-dominant, which means that if both are present, then the child will have both A and B markers. (Hence the AB blood type.)
