Coding strands

Unlike what happens in DNA replication, where both strands are copied, only one of the two DNA strands is transcribed into mRNA. The strand that contains the gene is often called the coding strand, or primer strand, and the strand that gets transcribed is called the template strand. Because the template strand and the coding strand are complementary, and because the template strand and the transcribed RNA are also complementary, the RNA )no ecule produced during transcription is a copy of the DNA coding strand. The only difference is that the RNA molecule has a U everywhere the DNA coding strand has a T. 

What amino acid sequence is coded by the following segment of a DNA coding strand ... 

The mRNA produced during translation is a copy of the DNA coding strand, with each T replaced by U. Thus, the mRNA has the sequence... 

Coding strand (Section 28.4) The strand of double-helical DNA that contains the gene. 

Coconut oil, composition of, 1062 Coding strand (DNA), 1108 CODIS, DNA fingerprint registry, 1118... 

Transcription (DNA), 1108-1109 coding strand in, 1108 primer strand in, 1108 promoter sites in, 1108 template strand in, 1108 Transfer RNA, 1108... 

Figure 35-8. The relationship between the sequences of an RNA transcript and its gene, in which the coding and template strands are shown with their polarities. The RNA transcript with a 5 to 3 polarity is complementary to the template strand with its 3 to 5 polarity. Note that the sequence in the RNA transcript and its polarity is the same as that in the coding strand, except that the U of the transcript replaces theT of the gene.

Figure 37-1. This figure illustrates that genes can be transcribed off both strands of DNA. The arrowheads indicate the direction of transcription (polarity). Note that the template strand is always read in the 3 to 5 direction. The opposite strand is called the coding strand because it is identical (except for T for L) changes) to the mRNA transcript (the primary transcript in eukaryotic cells) that encodes the protein product of the gene.

Figure 37-2. RNA polymerase (RNAP) catalyzes the polymerization of ribonucleotides into an RNA sequence that is complementary to the template strand of the gene. The RNA transcript has the same polarity (5 to 3 ) as the coding strand but contains L) rather than T. E coli RNAP consists of a core complex of two a subunits and two p subunits (P and p ). The holoen-zyme contains the 0 subunit bound to the ajPP core assembly. The co subunit is not shown. The transcription "bubble" is an approximately 20-bp area of melted DNA, and the entire complex covers 30-75 bp, depending on the conformation of RNAP.

By convention, the base sequence of a gene is given from the coding strand (S —>3 ). 

The answer is A. Because all nucleic acids are synthesized in the 5 to 3 direction, mRNA and the coding strand of DNA must each be oriented 5 to 3, i.e., in the direction of transcription. This means that the bottom strand in this example is the coding strand. The top strand is the template strand. 

Identify the coding strand of DNA from the direction of transcription,... 

Find the option with a sequence identical to the coding strand (remember to substitute U for T, if necessary). 

Answer D. Since the sequence in the stem represents the coding strand, the mRNA... 

Answer D. The complementary probe will be antiparallel to the coding strand of the... 

More recently, we have extended this study of strand asymmetries in intron sequences to evolutionarily distant eukaryotes [37]. When appropriately examined, all genomes present transcription-coupled excess of T over A ( TA > 0) in the coding strand. In contrast, GC skew is found positive in... 

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