Explain how transcription of genes occurs

Transcription occurs in the nucleus of the cell.The enzyme DNA helicase catalyses the 'unzipping' or splitting of the two DNA chains in the region of the gene by catalysing the breaking of the hydrogen bonds holding the chains together.RNA polymerase catalyses complementary mRNA nucleotides to form a complementary strand with the exposed bases. mRNA bases are ACGU rather than ACGT as in DNA.The mRNA then leaves the nucleus to carry the information of how to make the protein coded by the gene to the ribosomes. Each gene codes for the formation of one protein.The mRNA is a very small molecule and so can pass through the nuclear pore into the cytoplasm to travel to the ribosomes.