Use the figure to answer the following question.

A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in ¹⁵N medium for several generations and then transfer them to ¹⁴N medium. Which pattern in the figure would you expect if the DNA was replicated in a conservative manner?
A) A
B) B
C) C
D) D

Question

Use the figure to answer the following question.

A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in ¹⁵N medium for several generations and then transfer them to ¹⁴N medium. Which pattern in the figure would you expect if the DNA was replicated in a conservative manner?
A) A 
B) B 
C) C 
D) D

Quizplus · Accepted Answer

If DNA was replicated in a conservative manner, the old strand would act as a template for the synthesis of a completely new strand. This would result in two distinct bands, one with both strands labeled with ¹⁵N (heavy) and the other with both strands labeled with ¹⁴N (light), as seen in option B. Option A shows a pattern expected if DNA was replicated in a dispersive manner, option C shows a pattern expected if DNA was replicated in a semiconservative manner, and option D does not show any visible differences between the heavy and light DNA.

Use the Figure to Answer the Following Question