The transcription takes place in the nucleus. This process involve copying of DNA sequence into mRNA (messenger RNA) sequence. mRNA too consists of 4 nucleotides except the fact that in mRNA the thymine (T) is replaced by uracil (U). This involves the following steps:
Unwinding of DNA
Binding of RNA polymerase to the unwinded DNA.
Synthesis of RNA commonly mRNA
RNA elongation
Stop codon (UAA, UAG, UGA) initiating termination of synthesis of RNA
