Hi, can anyone explain to me how blood groups are pasted on to children through their parents?

Question

I understand that phenotype and genotype have something to do with this process but i'm not sure how this works. Thank you x

Answer 1

Blood groups are coded by genes on the chromosomes. You get one set of 23 chromosomes from the mother and one set of 23 from the father for a total of 46 chromosomes.

So, if the mother has a genotype of AO for example, this makes a type A phenotype and this is her blood type because O is recessive and without two copies of O you will not get the O phenotype. In her eggs, there is a 50/50 shot at either having the gene that codes for A or the gene that codes for O - an egg will not have both the A and the O.

If the father has a genotype of AB, AB is his phenotype and blood type is AB, because A and B are codominant and neither are recessive. In his sperm, there will be either the gene for A or the gene for B.

So, possible combinations for offspring would be as follows if you made a Punnett Square:

genotype AA = A phenotype and blood type
genotype AB = AB phenotype and blood type
genotype BO = B phenotype and blood type
genotype AO = A phenotype and blood type

The Rh factor, positive or negative, is determined the same way.

Answer 2

Everything Jill said is right. But, I will add, nothing inherited gets "pasted on" to children.

When sperm and egg cells meet and combine, each is part of the parent it came from. After combination, the newly formed cell starts to divide with its unique combination of genes from each parent.