What is the characteristic structure of catalytic RNA?

The characteristic structure of catalytic RNA, also known as ribozymes, is primarily single-stranded. This single-stranded nature allows catalytic RNA to fold into intricate three-dimensional shapes that are essential for their enzymatic activity. The specific folding patterns enable ribozymes to form active sites where they can catalyze biochemical reactions, just like protein enzymes do.

While there are various types of RNA, including double-stranded RNA in some viruses and structures like triple helixes in specific contexts, these configurations do not apply to the catalytic functions of RNA. Additionally, the idea of a four base strand does not represent a known structure within ribozymes or RNA in general.

Thus, the mind-set that catalytic RNA is single-stranded is crucial for understanding how these molecules can effectively function and participate in various biological reactions, differentiating them from other forms of nucleic acids.