A-LevelBiologyNucleic acids and protein synthesis9700/12 · May/June 2016 · Q201 Mark
Bacteria were grown in a medium containing 15N. After several generations, all of the DNA contained 15N. Some of these bacteria were transferred to a medium containing the common isotope of nitrogen, 14N. The bacteria were allowed to divide once. The DNA of some of these bacteria was extracted and analysed. This DNA was all hybrid DNA containing equal amounts of 14N and 15N. The remaining bacteria were left in the medium with 14N and allowed to divide one more time. The DNA of some of these bacteria was extracted and analysed. What is the composition of this DNA?
A25% hybrid DNA
B50% hybrid DNA
C75% hybrid DNA
D100% hybrid DNA
✓ Correct answer
B: 50% hybrid DNA
Practise more questions on this topic
Oracle Prep sorts past-paper questions by topic, so you can drill Nucleic acids and protein synthesis and see which topics are most likely to come up next.
Sign up free →