Q. Genetic code is made up by the four-letter alphabet forming the pairs?
Answer: A—T, T—A, C—G, G—C
Notes: The four letters designating these bases (A, G, C, and T) are the alphabet of the genetic code. Each rung of the DNA molecule is contains a combination of two of these letters, one jutting out from each side. In this genetic code, A always combines with T, and C with G to make what is called a base pair.