Video Transcript
During transcription, what base in the mRNA strand will an adenine base in the DNA template strand bind to?
In order for a gene in DNA to be converted into a protein, it needs to go through a couple of steps. The first step is transcription and is where the gene in DNA is copied to form an mRNA transcript. The sequence of nucleotides in mRNA can then be translated into a sequence of amino acids to form a polypeptide. This polypeptide can then go on to fold into a protein.
This question is asking us about transcription, so let’s review that in some detail.
The major enzyme of transcription is called RNA polymerase, and it first binds to the promoter region of a gene in DNA. Next, RNA polymerase unwinds the double-stranded DNA molecule. It does this by breaking the hydrogen bonds between base pairs. Now that the bases on DNA are exposed, free RNA nucleotides can be added to form a strand of complementary mRNA to the DNA template strand.
Base pairing between RNA and DNA is similar as it is between the two strands of DNA with one exception. Normally, adenine binds to thymine in DNA, but in RNA there is no thymine. Instead, RNA contains uracil, which binds to adenine instead of thymine. As transcription continues, the strand of mRNA gets longer as RNA polymerase moves along DNA and adds new nucleotides. Once a stop signal is reached in the gene in DNA, the mRNA is released so it can exit the nucleus to be translated into a polypeptide, which can then fold into a protein.
Getting back to our question, the base in mRNA that will bind to adenine on the DNA template strand during transcription is uracil.
