Fone possesses one allele for blood group a antigen and one allele for blood group b, he will have type ab blood, distinctly different from both a and b. this type of inheritance is called

Codominance

Explanation:

According to the given information, an individual carries one allele for blood group A antigen and one allele for the blood group B. Let's assume that the allele I^A imparts blood type "A" while the allele I^B is responsible for blood type B. Now, the genotype of the individual is I^AI^B and its phenotype is blood type "AB".

When both the alleles of a gene are expressed in a heterozygote and the phenotype of the heterozygote is distinct from both the pure breeding parents, the pattern of inheritance is called codominance. The I^A and I^B alleles codominant as both are equally expressed in the heterozygote.

regulation of gene expression. gene expression can be regulated by various cellular processes with the aim to control the amount and nature of the expressed genes. these regulatory proteins bind to dna and send signals that indirectly control the rate of gene expression

explanation:

not sure if this is what you'r looking for eubacteria and archaebacteria