| 1. | 3' (downstream) end and 5' (upstream) end, respectively of the transcription unit |
| 2. | 5' (upstream) end and 3' (downstream) end, respectively of the transcription unit |
| 3. | the 5' (upstream) end |
| 4. | the 3' (downstream) end |
| 1. | DNA molecule being synthesised is very long |
| 2. | DNA dependent DNA polymerase catalyses polymerisation only in one direction (5’ → 3’) |
| 3. | it is a more efficient process |
| 4. | DNA ligase joins the short stretches of DNA |