What type of bonds form between nucleotides during transcription?

• A. Hydrogen bonds
• B. Phosphodiester bonds
• C. Peptide bonds
• D. Glycosidic bonds

Answer: (B)

The bonds that hold the RNA chain together are phosphodiester bonds. As transcription proceeds, each new ribonucleotide is added to the growing RNA strand by a condensation reaction that links the 3' hydroxyl of the existing sugar to the 5' phosphate of the incoming nucleotide, forming a covalent phosphodiester linkage and releasing pyrophosphate. This creates the sugar–phosphate backbone of the RNA. Hydrogen bonds, on the other hand, stabilize base pairing (A–U and G–C) between strands or within RNA structures, but they do not join nucleotides along the backbone. Peptide bonds connect amino acids in proteins, and glycosidic bonds connect sugars in carbohydrates, so they aren’t the bonds forming during RNA transcription.