Is The Coding Or Template Starand On Top
Template vs Coding Strands
It is often useful to distinguish the two strands of DNA -- the strand that is copied into mRNA and after translated has the complementary sequence to the mRNA, while the base sequence of the opposite strand directly corresponds to the codons in the mRNA.
The terms template strand, sense strand, and coding strand are commonly used to describe ane of the two strands of Dna, yet the classification is quite confusing because different authors have used these terms to describe both strands -- 1 school argues that the strand copied into mRNA should be considered the template strand, but the other school argues that the reverse strand which reflects the sequence in the mRNA should exist considered the template because the corresponding codons are copied into protein. The beginning definition is used in the figures below, however, to avoid defoliation, when using the words template, sense, or coding, it is essential to explicitly define how you lot are using the terms. I believe that these terms are best divers as described below.
The term template strand refers to the sequence of DNA that is copied during the synthesis of mRNA.
The contrary strand (that is, the strand with a base of operations sequence directly corresponding to the mRNA sequence) is called the coding strand or the mRNA-similar strand because the sequence corresponds to the codons that are translated into poly peptide.
Although RNA polymerase must recognize sequences on the template strand, past convention we draw the Dna sequence and regulatory signals on the "mRNA-similar" strand. (This makes it simpler to directly make up one's mind the sequence of the resulting RNA.) The following drawing shows this concept for a hypothetical gene.
Information technology may be useful to consider a real gene as well. The Dna sequence of the phage P22 arc factor and some of import regulatory sites is shown beneath. The upper strand of DNA is the "mRNA-like" strand. The lower strand is the strand that is complementary to the mRNA. The -35 region (TTGACA) and -10 region (TATATT) of the promoter sequence and the transcriptional start site (the A ) is indicated on the coding strand. Also note that the DNA sequence of the coding strand corresponding to the RNA codons is shown in assuming (of course, the T is a U in the RNA) -- the showtime codon is ATG the translational kickoff site (fMet) and the last codon is TAA (Ochre) the translational stop codon.
References:
- Arc DNA sequence from Genbank
- Rex, R., and Due west. Stansfield. 1985. A dictionary of genetics. Oxford Academy Press, NY.
Please ship comments, suggestions, or questions to smaloy@sciences.sdsu.edu
Final modified July 12, 2002
Is The Coding Or Template Starand On Top,
Source: http://sci.sdsu.edu/~smaloy/MicrobialGenetics/topics/chroms-genes-prots/temp-strand.html
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