Question

The Shine-Dalgarno sequence in bacteria ________. a) is a purine-rich consensus sequence found in the 5ʹ UTR of the mRNA b) is a pyrimidine-rich consensus sequence found in the 3ʹ UTR of the mRNA c) is a purine-rich consensus sequence found

Answer 1

Answer:

The correct answer is a) is a purine-rich consensus sequence found in the 5ʹ UTR of the mRNA.

Explanation:

The mRNA of bacteria contains Shine- Dalgarno sequence and initiation codon which together make up the ribosomal binding site. The Shine-Dalgarno sequence(5'- AGGAGGU-3') is a short polypurine sequence that is found at 5' end of UTR of the mRNA.  

Shine-Dalgarno sequence is found 3-10 nucleotides upstream to start codon(AUG). This sequence is complementary to a region of the 16S rRNA component of small ribosomal units found in bacteria.  

So Shine-Dalgarno sequence play an important role in the attachment of small ribosomal subunit of bacteria and recognition of start codon. So the right answer is a.