Question

Eukaryotic messenger RNA undergoes several processing steps after transcription before it binds to ribosomes as the template for protein synthesis. One of these steps is polyadenylation. Identify whether the statements below about polyadenylation are true or false. A polymerase adds a polyadenylate tail of about 10 nucleotides to the 3' end of the mRNA. A polymerase adds a polyadenylate tail to the mRNA while it is still in the nucleus. The polymerase forming the polyadenylate tail uses a polydT DNA template strand. The polyadenylate tail helps to protect the mRNA from exonucleases. Polyadenylation can occur before or after the mRNA is spliced. The mRNA for what eukaryotic proteins are not polyadenylated?

Answer 1

1. False:

Reason:A polyadenylate tail is known to add upto 100 to 250 nucleotides at the 3' end of mRNA.

2. True.

Reason:The 3' tails are added to mRNA in the nucleus that protects the mRNA from degradation by exonucleases when it reaches the the cytoplasm for translation.

3. False.

Reason:The polymerase forming the capping at 3' end does not use a polydT DNA as a template.

4. True

Reason:The polyadenylate tail protects the mRNA against degrdadtion by exonucleases when it is transported to cytoplasm to carry out translation.

5. True

6. In eukaryotes,most histone proteins mRNAs are not polyadenylated.