Question

Which nucleic acid often forms intramolecular base pairs with itself to fold into complex three-dimensional shapes in the cell?

1) DNA
2) RNA
3) Protein
4) Lipid

Answer 1

RNA is the nucleic acid that can form intramolecular base pairs with itself, allowing it to take on complex 3D shapes that are critical for its function in the cell.

Step-by-step explanation:

RNA and Intramolecular Base Pairing

The nucleic acid that often forms intramolecular base pairs with itself to fold into complex three-dimensional shapes in the cell is RNA (ribonucleic acid). Unlike DNA, which is typically found in cells as a double-stranded helix, RNA is single-stranded. However, RNA strands can and often do fold onto themselves, forming hairpin structures and other shapes due to the hydrogen bonding between complementary base pairs. This folding is critical to the molecule's function. For instance, the various forms of RNA such as mRNA, tRNA, and rRNA gain their functionality through their specific secondary and tertiary structures, which are reliant on these intramolecular interactions.

The backbone of RNA consists of a chain of sugars and phosphate groups, with nitrogenous bases extending from the sugar. These bases can form hydrogen bonds with complementary bases within the same molecule, creating intricate secondary structures important for the RNA's function in processes like protein synthesis, gene regulation, and many others.