Understanding DNA Transcription: Decoding the Role of Non-Coding Strands"

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In summary, transcription occurs on the non-coding strand because it serves as the template for creating an identical copy of the coding strand. It would be pointless to create a copy of the non-coding strand, which is inert and has no functional role in protein coding. The terms "template" and "complementary" strands are sometimes used to refer to the non-coding and coding strands, respectively. However, the definitions of coding and non-coding are ultimately arbitrary and depend on the context and perspective.
  • #1
gfd43tg
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Hello,

How is it that transcription occurs on the non-coding strand? If you are to code for proteins, wouldn't it want to do the transcription on the coding strand? This is puzzling me
 
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  • #3
I think I get it now. So, it will base pair with the non-coding strand so that it has an identical copy of the coding strand. It would be useless to create a copy of a non-coding strand, since a non-coding strand is "inert" so to speak and won't be functional. I know that is vague terms but not sure exactly the right way to say it.
 
  • #4
The way I learned it in my Biology course was by referring to the strands as complementary and template strands. The template strand is the non-coding strand - template is a more intuitive way of thinking of it (for me, anyway). The complementary strand has a base sequence that is complementary to the RNA sequence, and to the template strand, hence the name.

I personally find this easier to use, however, if this is used and words like coding and non-coding strands are required, you would have to take care when "translating" the terms to what is expected of you.
 
  • #5
The template strand is complementary to the mRNA sequence because RNA polymerase synthesizes a RNA complementary to its template. Thus, the non-template strand (which is complementary to the template strand) has a sequence identical to the mRNA (except for the replacement of Ts for Us).
 
  • #6
The definitions are ultimately arbitrary. Coding sequence is defined as that of the mRNA, which is the reverse complement of the DNA strand which was read and transcribed by RNA polymerase, so by definition the physical strand of DNA read is the non-coding strand. For simplicity's sake, we usually look at the DNA strand sequence which is the same as the mRNA for information content, even though that is not the strand that is physically read by the polymerase.
 

1. What is transcription in DNA?

Transcription is the process by which a segment of DNA is copied into a complementary strand of RNA. This RNA strand, called messenger RNA (mRNA), carries the genetic information from the DNA to the ribosomes where it is used to create proteins.

2. What is the purpose of transcription?

The purpose of transcription is to convert the genetic information stored in DNA into a format that can be easily read and translated into proteins. This allows for the expression of genes and the production of proteins necessary for various cellular processes.

3. What are the steps involved in transcription?

The first step in transcription is initiation, where an enzyme called RNA polymerase binds to a specific region of the DNA called the promoter. Next, the enzyme unwinds and separates the two strands of DNA. Then, elongation occurs where the enzyme moves along the DNA and adds complementary RNA nucleotides to create the mRNA strand. Finally, termination occurs when the RNA polymerase reaches a special sequence of DNA called the terminator and releases the mRNA strand.

4. How is transcription different in eukaryotes and prokaryotes?

In prokaryotes, transcription occurs in the cytoplasm and translation (protein synthesis) occurs simultaneously. In eukaryotes, transcription occurs in the nucleus and the mRNA must be transported out of the nucleus to the cytoplasm for translation. Additionally, eukaryotic DNA contains non-coding regions called introns which must be removed from the mRNA before it can be used for protein synthesis.

5. What factors can affect transcription?

There are several factors that can affect transcription, including the presence or absence of specific transcription factors, the accessibility of the DNA sequence, and the presence of regulatory sequences such as enhancers or silencers. Environmental factors, such as stress or exposure to certain chemicals, can also impact transcription by altering the activity of transcription factors or modifying the DNA sequence itself.

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