Question

The enzyme DNA dependent RNA polymerase and DNA dependent DNA polymerase catalyse the polymerisation reaction in ___(i)_____ and ___(ii)_____ direction, respectively.

• A. i- 3'→5', ii- 5'→3'
• B. i- 5'→3', ii- 5'→3'
• C. both a and c
• D. i- 5'→3', ii- 3'→5'

Answer 1

The correct option is B i- 5'→3', ii- 5'→3'

The DNA dependent DNA polymerase helps in the replication or duplication of DNA.

The two strands of DNA have opposite polarity and still the DNA dependent DNA polymerase catalyses the polymerisation in only one direction, that is, 5'→3'.

This leads to the formation of a continuous and discontinuous strand. The discontinuous strand of DNA has small fragments of DNA called okazaki fragments which are joined by DNA ligase.

The DNA dependent RNA polymerase helps in the transcription of DNA into RNA. Only one strand of DNA acts as a template (3'→5') and gets transcribed into RNA in 5'→3' direction only.