This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
what does not occur in 5'- 3'direction? 
Select and explain. 
A. DNA repair, B. DNA replication, C. RNA editing, D. Transcription
C: RNA editing
Answer: C: RNA editing 
Explanation: Ans -C- RNA editingIn rna editing editosome can edit only in 3- 5 direction, along with primary rna transcript.DNA replication goes in the 5' to 3' direction because DNA polymerase acts on the 3'-OH of the existing strand for adding free nucleotides.In transcription the complementary RNA is created in the opposite direction, in the 5' - 3' direction, matching the sequence of the sense strand with the exception of switching uracil for thymine.When the strand containing the mis-match is identified, an endonuclease nicks the strand and the mis-matched nucleotide(s) is/are removed by an exonuclease.