While it is relatively easy to define what a hurricane or earthquake is, defining a drought is more subjective. Droughts do not have the immediate effects of floods, but sustained droughts can cause economic stress throughout an area. The word drought has various meanings, depending on a person's perspective.
For the software package, see Partition function for Interacting RNAs. Piwi-interacting RNA (piRNA) is the largest class of small non-coding RNA molecules expressed in animal cells. piRNAs form RNA-protein complexes through interactions with piwi proteins.
Ribonucleic acid (RNA) is a linear molecule composed of four types of smaller molecules called ribonucleotide bases: adenine (A), cytosine (C), guanine (G), and uracil (U).ach ribonucleotide base consists of a ribose sugar, a phosphate group, and a nitrogenous base. Adjacent ribose nucleotide bases are chemically attached to one another in a chain via chemical bonds called phosphodiester bonds. Unlike DNA, RNA is usually single-stranded.