What are Double Stranded DNA and mRNA sequences?

A Double Stranded DNA sequence actually contains two nucleotide strands. Here is a made-up example:

DNA coding strand (aka Crick strand, strand +1)
  5' ATGGCCATTGTAATGGGCCGCTGAAAGGGTGCCCGATAG 3'

DNA template strand (aka Watson strand, strand −1)
which is the reverse complement of the coding strand
  3' TACCGGTAACATTACCCGGCGACTTTCCCACGGGCTATC 5'

The mRNA is derived from the biological transcription process, which does a reverse complement (TCAG → CUGA) from the DNA template strand.

Single stranded mRNA
5' AUGGCCAUUGUAAUGGGCCGCUGAAAGGGUGCCCGAUAG 3’ 

We can simulate this biological transcription process using the transcribe() function.

fyicenter$ python
>>> from Bio.Seq import Seq
>>> coding_dna = Seq("ATGGCCATTGTAATGGGCCGCTGAAAGGGTGCCCGATAG")
>>> coding_dna
Seq('ATGGCCATTGTAATGGGCCGCTGAAAGGGTGCCCGATAG')

>>> template_dna = coding_dna.reverse_complement()
>>> template_dna
Seq('CTATCGGGCACCCTTTCAGCGGCCCATTACAATGGCCAT')

>>> messenger_rna = coding_dna.transcribe()
>>> messenger_rna
Seq('AUGGCCAUUGUAAUGGGCCGCUGAAAGGGUGCCCGAUAG')

We can also convert the mRNA (messenger_rna) back to the DNA coding strand, using the back_transcribe() function.

>>> coding_dna = messenger_rna.back_transcribe()
>>> coding_dna
Seq('ATGGCCATTGTAATGGGCCGCTGAAAGGGTGCCCGATAG')

⇒ mRNA, Protein and Translation

⇐ Play with the Bio.Seq Module

⇑ Biopython - Tools for Biological Computation

⇑⇑ OBF (Open Bioinformatics Foundation) Tools