Читать книгу Principles of Microbial Diversity - James W. Brown - Страница 24

RNA is used primarily to direct protein synthesis based on information in DNA. RNA in all cells has the same structure, the same four bases (G, A, U, and C) and sugar (D-ribose), and the same stereochemistry. Furthermore, all cells have the same types of RNAs, e.g., ribosomal RNA (rRNA), transfer RNA (tRNA), messenger RNA (mRNA), and so forth. These RNAs are very much alike in sequence and structure in all cells; for example, the rRNAs in all organisms share a conserved core of sequence and are very similar in secondary structure (Fig. 1.11).