THE MOLECULAR BASIS OF INHERITANCE
DNA MAKES RNA MAKES PROTEIN
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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to add modified guanin to the 3’ end of the mRNA
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to indicate the site of translational termination
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to code for the binding of RNA polymerase to the DNA
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to help protect the mRNA from degradation by hydrolytic enzymes
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Detailed explanation-1: -Function. In nuclear polyadenylation, a poly(A) tail is added to an RNA at the end of transcription. On mRNAs, the poly(A) tail protects the mRNA molecule from enzymatic degradation in the cytoplasm and aids in transcription termination, export of the mRNA from the nucleus, and translation.
Detailed explanation-2: -The poly-A tail makes the RNA molecule more stable and prevents its degradation. Additionally, the poly-A tail allows the mature messenger RNA molecule to be exported from the nucleus and translated into a protein by ribosomes in the cytoplasm.
Detailed explanation-3: -Poly(A) tails provide toeholds where polynucleotide phosphorylase can initiate exonucleolytic degradation of tightly folded RNAs protected from exoribonucleases by 3’ stable secondary structures.
Detailed explanation-4: -Function. Poly(A) Polymerase (polynucleotide adenylytransferase, EC 2.7. 7.19) is the enzyme responsible for adding a polyadenine tail to the 3’ end of a nascent pre-mRNA transcript. Its substrates are ATP and RNA.
Detailed explanation-5: -Most eukaryotic mRNAs have a 3′ tail of 50 to 200 adenine residues added posttranscriptionally to the 3′ end (see Fig. 11.3). This poly(A) tail binds a protein that promotes export from the nucleus and protects the mRNA from degradation in the cytoplasm. The 3′ poly(A) tails are shorter or absent on bacterial mRNAs.