Question

Which of the following statements about linkage of bases to the sugar are true? Select the two true statements.

In purines, the N-1 atom is covalently bonded to the C-1' of the sugar.
In purines, the N-9 atom is covalently bonded to the C-1' of the sugar.
In pyrimidines, the N-1 atom is covalently bonded to the C-1' of the sugar.
In pyrimidines, the N-9 atom is covalently bonded to the C-1' of the sugar.

Answer 1

The true linkage patterns are that purines bond to the sugar via N-9 and pyrimidines via N-1.

Step-by-step explanation:

The linkages between the pentose sugar and the nitrogenous bases differ between purines and pyrimidines. Purines, which are the larger bases with a double-ring structure that includes adenine (A) and guanine (G), are linked to the sugar molecule via the nitrogen atom present at the ninth position (N-9) to the C-1' of the sugar. In contrast, the smaller pyrimidines, which include cytosine (C) and thymine (T) with a single-ring structure, are linked to the C-1' of the sugar through the nitrogen atom present at the first position (N-1).

Therefore, the true statements regarding the linkage of bases to the sugar are: In purines, the N-9 atom is covalently bonded to the C-1' of the sugar and in pyrimidines, the N-1 atom is covalently bonded to the C-1' of the sugar.