For the oligoribonucleotide pACGUAC:
A)the nucleotide at the 3' end has a phosphate at its 3' hydroxyl.
B)the nucleotide at the 3' end is a purine.
C)the nucleotide at the 5' end has a 5' hydroxyl.
D)the nucleotide at the 5' end has a phosphate on its 5' hydroxyl.
E)the nucleotide at the 5' end is a pyrimidine.

Question

Quizplus · Accepted Answer

The oligoribonucleotide pACGUAC consists of nucleotides containing A, C, G, and U bases, but we cannot determine the sequence from the given information. However, we can make some generalizations about the ends of the oligoribonucleotide. The 3' end of an oligoribonucleotide always has a free hydroxyl (-OH) group on the sugar of the last nucleotide, but since this oligoribonucleotide is abbreviated, we can't tell if the last nucleotide has a phosphate group attached to its 3' hydroxyl. However, we can say that the nucleotide at the 5' end of the oligoribonucleotide must have a phosphate group attached to its 5' hydroxyl, since that is how ribonucleotides are linked together in RNA. Therefore, the correct choice is D, which states that the nucleotide at the 5' end has a phosphate on its 5' hydroxyl.

For the Oligoribonucleotide PACGUAC