Template and non template strands transcription

Question 1

In the transcription stage of protein synthesis, the section of the DNA molecule where the gene is located (the gene coding for a particular polypeptide) unwinds – the hydrogen bonds between the complementary base pairs break, causing the two DNA strands to ‘unzip’

Free activated RNA nucleotides then pair up with the exposed bases on the DNA molecule but only with those bases on one strand of the DNA molecule

This strand of the DNA molecule is called the

Answer 1

template strand or the transcribed strand

This is the strand that is transcribed to form the mRNA molecule (RNA polymerase binds the RNA nucleotides together to create the sugar-phosphate backbone of the mRNA molecule)

This mRNA molecule will then be translated into an amino acid chain

Question 2

The strand of the DNA molecule that is not transcribed is called the

Answer 2

non-template strand or the non-transcribed strand

Question 3

Be careful – DNA polymerase is the enzyme involved in DNA replication; RNA polymerase is the enzyme involved in transcription – don’t get these confused.

Note the use of sense and anti-sense strands in transcription has been replaced with non-transcribed and transcribed (or template) strands respectively.

The mRNA codons have the same base sequence as the non-transcribed strand, and the tRNA anticodons have the same base sequence as the transcribed strand except RNA, which has the base Uracil, replacing Thymine.