Like DNA, RNA is a linear polymer made of four different types of nucleotide subunits linked together by phosphodiester bonds ( Figure 6-4). The information in RNA, although copied into another chemical form, is still written in essentially the same language as it is in DNA-the language of a nucleotide sequence. The first step a cell takes in reading out a needed part of its genetic instructions is to copy a particular portion of its DNA nucleotide sequence-a gene-into an RNA nucleotide sequence. Portions of DNA Sequence Are Transcribed into RNA
