Shu Xiang Jing Si 2006-08-26 20:37:2 1
A person's blood type refers to all kinds of blood group antigens on the surface of individual red blood cells, which are determined by genetic material-genes. If a person has genes, it can be confirmed that there is antigen A on the surface of his red blood cells. Moreover, the relationship between blood group gene and blood group antigen is single, that is, there must be a gene related to antigen. In addition, the relationship between gene and blood group antigen expression is generally not affected by environmental conditions. Generally speaking, the genes related to blood type are mostly isodominant genes, that is, some alleles on autosome, and there is no dominant or recessive relationship between them. In the state of heterozygosity, the functions of the two genes can also be expressed, and the gene products are produced independently. This mode of inheritance is called * * * dominance or isodominance, and the inheritance of ABO blood group is * * * dominance inheritance. A and B are dominant genes, and O is recessive gene. Because chromosomes appear in pairs, everyone has two genes to control blood type. When a person's genes are A and B, the dominant genes are expressed, and the blood type is AB. When the genes are A and O or B and O, they are also dominant genes, so the gene of O cannot be expressed, and the blood type is A or B respectively. Only when both genes are recessive gene O, the blood type is AB. Therefore, the genes of people with blood types A and B may be AA, BB, AO and BO. Aa and bb are homozygotes, ao and bo are heterozygotes, and the human gene of type O blood is OO.
The gene locus of ABO blood group system is on chromosome 9. Human ABO blood group is controlled by three genes: A, B and O, but there are only two ABO system genes on chromosome 9 in each cell, which are a pair of alleles among AO, AA, BO, BB, AB and OO, in which A and B genes are dominant genes and O gene is recessive.
Therefore, the genetic law of blood type is as follows
A+A→A、O；
A+B→A、B、O、AB；
A+O →A、O；
A+AB→A、B、AB；
B+B→B、O；
B+O→B、O；
B+AB→B、A、AB；
O+O→O；
O+AB →A、B；
AB+AB→AB、AB .
The discovery is for reference only, and I don't understand it either.