WHy do more people have bloold type O if it is recessive to A and B. why are recessive genes more common?

Question

there are three alelles for boold type AB and i which ii is O. is you end up with ii, but Ai is A type, Bi is B, and AB is AB type blood.

Answer 1

I posted this before, but it still applies here:


It isn't that recessive genes or dominant genes are more common. What usually happens is the the mutant is less common.

There are multiple types of effects that result from mutations. The most common effect is a loss of function. Loss of function mutations result in recessive phenotypes (because one good copy of the gene still gives you the phenotype), thus they are recessive alleles. In these cases, usually the recessive gene is the minority.

Some mutations result in gain of function, that is they cause a new protein that causes a new phenotype. Now all you need is a single copy of this mutated gene to get the phenotype, hence it is dominant. In these cases, the dominant allele is the minority (e.g. blood types).

Over time selection and other factors change the gene frequencies, so that in the end there is no hard and fast rule about the frequency of dominant vs. recessive alleles.

Answer 2

Contrary to common perception, just because a gene is recessive does not make it rare. Whether a gene is recessive or not depends on the type of protein it produces, and is completely unrelated to the frequency of the gene.

However I can see your point, that as is it recessive, if everything else was equal there should be more As and Bs. The simple explanation is that A and B alleles are quite rare, whether through chance or an evolutionary function, I do not know.

Answer 3

The ABO blood system's genetics are not dominate/recessive. I believe it's a case of codominance.

Type O is actually the lack of additional antigens on the red cell's surface.

Type A and B are 2 different genes which codes for two different antigens (proteins.)

If the A gene is present, they will have A.
If the B gene is present, they will have B.
If both are present, they will have AB.
If neither is present, they will have neither, ie type O!

Answer 4

Blood type O is not recessive to A or B. It is the absence of the A or B antigen on the RBC surface.

Answer 5

it is because A & B blood groups are generally present in heterozygous state in society so when they mate chances are giving O also hence it is very common.

Answer 6

inbreeding ,acording to the bible we are all related