Each ribonucleotide base consists of a ribose sugar, a phosphate group, and a nitrogenous base ... messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). Although some RNA molecules ...

more nucleotides are added to the mRNA, thereby forming a progressively longer chain of nucleotides (Figure 2). This process is called elongation. Three of the four nitrogenous bases that make up ...