Dna Polymerase : Gene Expression, Transcription And Translation

1405 Words Sep 30th, 2016 6 Pages
DNA is the genetic material of cells and the production of RNA and/or proteins from the information stored in DNA is called gene expression. There are two steps in gene expression, transcription and translation.
Transcription starts off inside the cell, specifically where DNA resides, in the nucleus. The process of transcription is then executed by the enzyme, RNA polymerase which then makes mRNA. Here is a summary of the steps; First the RNA polymerase binds to the DNA strand at a specific nucleotide sequence of the gene (promoter). Then it unwinds and unlinks the two strands of DNA. After that it uses one of the DNA strands as a guide or template. Then it matches new nucleotides with their complements on the DNA strand (remember RNA has uracil instead of thymine). Then it binds these new RNA nucleotides together to form a complementary copy of the DNA strand (mRNA). Then it stops when it encounters a termination sequence of nucleotide bases which is the stop codon. mRNA could happily live in a single-stranded state (as opposed to DNA 's desire to form complementary double-stranded helix). In prokaryotes, all of the nucleotides in the mRNA are part of codons for the new protein. However, in eukaryotes only, there are extra sequences in the DNA and mRNA that don 't code for proteins called introns. This mRNA is then further processed the introns get cut out, the coding sequences get spliced together, a 7-methyloguanosine cap is added to one end of mRNA, and poly-A tail…
Open Document