This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: AIIMS 2019, Subject name: Biochemistry
Which of the following binds mRNA with ribosome in prokaryotes? 
Select and explain. 
A. tRNA, B. Shine Dalgarno sequence, C. 7 methyl guanosine capping, D. Poly A tail
B: Shine Dalgarno sequence
Answer: B: Shine Dalgarno sequence 
Explanation: Shine Dalgarno sequence Only in prokaryotes present at -10 position on mRNA, Rich in purines. SD sequence is complementary to 16 s rRNA, Their binding helps in binding of mRNA with ribosome during initiation of translation * In eukaryotic cells, ribosomes recognize most eukaryotic mRNAs by binding to the 7-methylguanosine cap at their 5' terminus.