What is type A+ blood?

Genes and blood types

First, an overview of blood

Blood consists of four components: plasma, red blood cells, white blood cells and platelets. Plasma accounts for about 55% of blood and is a mixture of water, sugar, fat, protein, potassium salt and calcium salt. It also contains many chemicals necessary to stop bleeding and form blood clots. Blood cells and platelets make up another 45% of the blood.

There are two kinds of blood cells: red blood cells and white blood cells. Most red blood cells look like rings with holes and can't wander around. Red blood cells contain a special protein called hemoglobin. This protein makes red blood cells look red. It can transport oxygen from the lungs to the whole body and concentrate carbon dioxide from the whole body to the lungs. Although blood contains many non-red blood cells, there are so many red blood cells that the blood itself is red.

White blood cells are round and much larger than red blood cells, which can produce a kind of protein called antibody to help the body resist infections caused by bacteria, viruses and foreign bodies.

Platelets are actually not cells, but fragments of cells. When we are injured, platelets gather and stick around the wound, producing chemicals that start the coagulation mechanism, and blood stops flowing.

Second, what is the blood type?

Everyone has a blood type. The most commonly used blood type classification method is ABO classification system invented by Karl Landsteiner in the early 1920s, including four blood types: A, B, AB and O. Your blood type is determined by the genes inherited from your parents before you were born. We inherited a large number of genes, half from mother and the other half from father. These genes combined to determine the blood type, thus producing a protein called agglutinin on the surface of red blood cells.

There are alleles of three blood group genes: A, B and O. Since everyone has copies of two genes, there are six possible combinations: AA, BB, OO, AB, AO and BO. In genetic terminology, these combinations are called genotypes and contain genes inherited from parents.

In addition to protein's lectin in red blood cells, other genes also produce a protein called coagulation hormone, which runs in plasma. The role of lectin is to ensure that there is only one blood type of blood cells in your blood.

Third, genotype determines blood type.

The lectin produced by O allele has no special enzyme activity, while the lectin produced by A and B alleles has its own enzyme activity. Therefore, people with OO genotype are type O blood, that is to say, the lectin on their red blood cells has no enzyme activity, and the blood will contain lectins A and B. Lectin A destroys type A blood cells that may enter the human blood circulation, and lectin B destroys type B blood cells.

People with AA genotype belong to type A blood because the lectin on their red blood cells has enzymatic activity. People with genotype AO also have enzyme activity related to allele A, so they also belong to type A blood. (Remember that the O allele has no enzymatic activity! ) People with type A blood have lectin B in their plasma, which destroys type B blood cells that enter the body's blood circulation.

Similarly, people with BB and BO genotypes belong to type B blood. These people have lectin A in their plasma, which will destroy any type B blood cells that enter the blood circulation.

People with genotype AB have enzyme activities related to both A and B alleles, and there is no lectin in their plasma.

The concepts of genotype and phenotype are easy to understand from the examples of blood types. Genotype refers to the real gene that a person has that determines a certain characteristic, and phenotype refers to the characteristics that a person shows. In the case of blood type, genotypes AA and AB make people show the phenotype of blood type A, and similarly, genotypes BB and BO show the phenotype of blood type B. People with phenotypes of O and AB can only have one genotype, namely OO and AB.

In different parts of the world, the population distribution of blood groups A, B, O and AB is different. The figure below shows the proportion of each blood type in different parts of the world.

O A group

USA: 289.499.438+032.080

Australia 427.391.115.066

Bolivia, India

China

Denmark: 423.434.5438+00 1.042

Eskimo: 472.452.059.5438+07

France: 10000.100000000005

Ireland+006.10060.000000000086

Nigeria

St Louis, Anna, USA, white +03.099. 59696.8888888866 1

African-Americans in Iowa, USA+0.265+0.265.20089.00000000005

The detection rate of blood type is determined by the number of A, B and O alleles found all over the world. When people from all over the world immigrate and mix on a larger scale, the distribution of different blood types will become more and more balanced.

Fourth, what is blood transfusion?

Because there are only four blood types, it is possible to draw blood from one person and input it to another. This is called blood transfusion. In order to make blood transfusion successful, it is necessary to make the lectin on the surface of donor red blood cells correspond to the lectin of recipient. In other words, the blood types of the donor and the recipient must match, otherwise the antibodies (lectins) in the recipient's blood will attack the blood cells of the donor and form blood clots through agglutination reaction.

If you need a blood transfusion, someone will take your blood sample to test your blood type and decide whose blood type it is. People with type A blood can receive blood from people with AA, AO and OO genotypes, while people with type B blood can receive blood from people with BB, BO and OO genotypes.

Five, two special blood types during blood transfusion: OO and AB.

People with type O blood are called universal blood donors because their blood can be donated to anyone, but they can only accept type O blood. Type O blood does not carry lectin A or B, and the immune system regards lectin as a foreign body. People with blood type O have lectins against lectins A and B, so if they have blood type A, B or AB, the body cannot avoid agglutination.

People with the second special blood type AB are called universal recipients because they can accept all four blood types. There are lectins A and B on the surface of red blood cells of type AB blood, and the body's immune system regards them as a part of itself-not a relic. Type AB blood can not produce agglutinin against agglutinin A and B, so type A, B, AB and O blood will not produce agglutination reaction.