University of Central Florida (UCF) PCB4524 Molecular Biology II Practice Exam 1

A ribozyme is an RNA molecule that possesses the ability to perform catalytic functions, much like a protein enzyme. This characteristic allows certain RNA molecules to catalyze biochemical reactions, which supports the idea of the "RNA world" hypothesis that posits RNA played a crucial role in the origin of life by both storing genetic information and facilitating biological reactions. Some well-studied examples of ribozymes include the self-splicing introns and the catalytic RNA in the ribosome, which helps in protein synthesis.

The other choices reference different biological molecules and functions: one suggests a role for proteins in RNA synthesis, another describes a DNA fragment's function in gene regulation, and the last mentions enzymatic modifications of ribosomes, all of which do not align with the defining feature of ribozymes as RNA molecules capable of catalysis.