AP BIOLOGY

Detailed explanation-1: -The four bases that make up this code are adenine (A), thymine (T), guanine (G) and cytosine (C). Bases pair off together in a double helix structure, these pairs being A and T, and C and G. RNA doesn’t contain thymine bases, replacing them with uracil bases (U), which pair to adenine1.

Detailed explanation-2: -Uracil (U) is one of the four nucleotide bases in RNA, with the other three being adenine (A), cytosine (C) and guanine (G). In RNA, uracil pairs with adenine. In a DNA molecule, the nucleotide thymine (T) is used in place of uracil.

Detailed explanation-3: -The rules of base pairing (or nucleotide pairing) are: A with T: the purine adenine (A) always pairs with the pyrimidine thymine (T) C with G: the pyrimidine cytosine (C) always pairs with the purine guanine (G)

Detailed explanation-4: -Because thymine has a higher resistance to photochemical mutation and makes the genetic code more durable, DNA uses it instead of uracil. This is required to store all the data required for life to function.

Detailed explanation-5: -Answer and Explanation: RNA uses uracil instead of thymine because RNA is already short-lived (compared to DNA) and errors don’t lead to long-lasting damage. Most importantly, uracil is less stable than thymine thereby making it easier to break down, as it is essentially a demethylated version of thymine.