Test your knowledge of RNA structure from secondary to tertiary and quaternary s...

RNA Structure: From Secondary to Tertiary and Quaternary Structures

• RNA performs various functions in the cell, including as genetic material in some viruses and contributing to polypeptide synthesis.
• In the 1980s, ribozymes were discovered, demonstrating that RNA molecules can act as catalysts.
• RNA structure, like protein structure, is divided into primary, secondary, tertiary, and quaternary structures.
• The primary sequence of an RNA molecule is its base sequence, while secondary structure is dominated by Watson-Crick base pairs.
• RNA's predominant secondary structure building blocks are helical tracts, which are stabilized by Watson-Crick base pairing.
• RNA tertiary structures are stabilized by interactions between two or more secondary structure elements, and metal cations such as Na+ and Mg2+.
• Specific structural elements contribute to the tertiary structure, such as pseudoknots, kissing hairpins, and hairpin loop-bulge contacts.
• RNA quaternary structure describes the arrangement of an RNA molecule with respect to other RNA molecules or with protein molecules.
• Some kinds of RNA molecules do not assume a specific three-dimensional structure but instead function as unstructured single strands.
• RNA's secondary structure consists of helical regions and various kinds of loops, bulges, and junctions within the helical regions.
• An internal loop forms when one or more nucleotides on each RNA strand are unpaired, and hairpin structures form when a strand folds back to form a stem that contains Watson-Crick base pairs and a loop.
• Crystal structures have been determined for many RNA molecules, including the hammerhead ribozyme, the smallest known RNA catalyst.