The DNA contains many regulatory sequences that are very important, even though they do not code for proteins.
For example, the expression of every gene is regulated by a region called the Promoter. The promoter sequence, located close by the coding region of the gene, usually binds the RNA polymerase (the enzyme that transcribes genes into mRNA) as well as other proteins necessary for transcription,
The promoter sequence, thus, does not itself code for proteins, but is essential for transcription and must be highly conserved so that the RNA polymerase can find it.
Answer: Those sequences do not code for proteins because the genes may be important and maybe should not be mutated. A mutation there could have a negative impact on an organism's ability to function effectively.
Explanation:
DNA transcription is the first process of gene expression, by which the information contained in the DNA sequence is transferred to the protein sequence using various RNAs as intermediaries. <u>During gene transcription, the DNA sequences are copied into RNA</u> by an enzyme called RNA polymerase (pRNA) which synthesizes a messenger RNA (mRNA) that maintains the DNA sequence information. In this way, DNA transcription could also be called messenger RNA synthesis. At last, that mRNA is used to make proteins in a process called translation.
<u>Those DNA sequences are transcribed, but not translated because they are able to regulate certain mRNA strands by destroying them or blocking translation of them</u>. So those DNA sequences are not used to make proteins, because a mutation there could have a negative impact on the organisms. Instead, those sequences may be used for other functions such as regulating gene expression by acting over other mRNA strands.
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