Question

Central dogma of molecular biology was modified with the discovery of

• A. Ligase
• B. RNA polymerase
• C. DNA polymerase
• D. Reserve transcriptase

Answer 1

The correct option is D Reserve transcriptase

• The molecular path of flow of genetic information is explained by central dogma. Accordingly, the flow of genetic information is unidirectional and involves four processes.
• Replication of DNA copies the genetic information present in it which is transcribed into RNA by RNA polymerase enzyme.
• The RNA sequence of ribonucleotides is translated into an amino acid sequence of polypeptides by the process of translation. Thus, the flow of genetic information is unidirectional and follows the path: DNA-RNA-protein.
• H. Temin and D. Baltimore showed that the retroviruses namely Rous sarcoma virus and the AIDS virus can make an RNA-dependent DNA polymerase that synthesizes a DNA copy (cDNA) of viral RNA. The cDNA is made into double stranded molecule which is integrated into host genome where it is replicated and transcribed with host DNA; the topsy curvy path of flow of genetic information, i.e., RNA-DNA-RNA-protein. The enzyme was termed as reverse transcriptase. The correct answer is D.
• DNA ligase joins two fragments together by phosphodiester linkage; DNA and RNA polymerases are enzymes of DNA replication and RNA synthesis that are involved in the unidirectional flow of genetic material.
• The correct answer is D.