0845 numbers, for example, are free to call for up to an hour, during the inclusive minutes of your call package if you're a BT customer. Yet call an 0844 number and you'll be charged up to 5.1p/minute, plus a connection fee of up to 15p.
The resulting mRNA is a single-stranded copy of the gene, which next must be translated into a protein molecule. During translation, which is the second major step in gene expression, the mRNA is read according to the genetic code, which relates the DNA sequence to the amino acid sequence in proteins (Figure 2).
The purpose of mRNA is to carry the genetic code from DNA to the ribosome for translation. mRNA is read in a series of triplets called codons. For example, the mRNA sequence AUGAAGCACUAC has four codons. Each codon corresponds to one amino acid.