A plasmid of 7 kb is present in a bacterial cell at a copy number of 120 per cell. Each base pair of DNA has a length of 0.34 nm. Calculate the total length of plasmid DNA present in a single cell in micrometres (µm).

Step-by-step solution

1. Compute the length of one plasmid: $7,000\text{bp}\times 0.34\text{nm/bp}=2,380\text{nm}$
2. Convert to micrometres: $2,380\text{nm}=2.38\mu \mathrm{m}$ per plasmid
3. Multiply by the copy number: $2.38\mu \mathrm{m}\times 120=285.6\mu \mathrm{m}$

Concept tested: Plasmid length calculation

Published 24 September 2026 · How this solution was prepared and checked