Q13 - Bacterial 23S rRNA Gene Copy Number
In bacteria, the molecular weight of the gene for 23S ribosomal RNA is 5.5 × 10⁵ daltons.
In an experiment, the total DNA of the bacteria had an optical density (OD) of 8.0 arbitrary units. The DNA encoding 23S rRNA had an optical density of 0.024 arbitrary units in the same sample volume. The arbitrary extinction coefficient of both sequences is 1.0 × 10⁹.
The molecular weight of the bacterial genome is 1.1 × 10⁹ daltons.
Q13.1. How many copies of the gene for 23S rRNA does a single bacterial genome contain? Write your answer rounded to the nearest whole number.
Question reproduced from IBO 2023, Theoretical Paper 1, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF