The building block of DNA is called the nucleotide, which is composed of a nitrogenous base (adenine, guanine, cytosine, or thymine), a five-carbon sugar (deoxyribose in DNA), â¦ and one to three phosphate groups. + 16 others found this useful.
Special cases of minimum ages and intervals. Two childhood vaccines require a bit more explanation regarding scheduling: â¢. MMR at age 1 year â Many statesâ school and childcare regulations specify that the minimum age for receipt of MMR vaccine be âon or after the first birthday,â with no allowance for a grace period.
MMR (Measles, Mumps, Rubella) 1  two doses of MMR are usually required by school entry. In the past, the second dose was given when a child was either 4 to 6 years old or 12 years old. 2  having two doses of MMR is important in this age of measles outbreaks.