Question

Which will absorb more UV light: dsDNA or ssDNA and why?

A) dsDNA, due to increased hydrogen bonding
B) ssDNA, due to increased surface area
C) dsDNA, due to increased base stacking
D) ssDNA, due to increased flexibility

Answer 1

dsDNA absorbs more UV light than ssDNA due to increased base stacking, which allows the nitrogenous bases in the DNA to efficiently absorb UV energy.

Step-by-step explanation:

Double-stranded DNA (dsDNA) will absorb more UV light compared to single-stranded DNA (ssDNA) because of increased base stacking interactions. Since dsDNA is structured with two strands forming a helical shape, the densely packed nature of base pairs allows for strong absorption of UV light. This absorption is due to the pi electrons in the nitrogenous bases that can absorb UV energy efficiently.

Therefore, the correct answer here would be C) dsDNA, due to increased base stacking. Despite having more surface area, ssDNA does not absorb more UV light than dsDNA because it lacks the organized base stacking which is crucial for strong UV absorption. Furthermore, hydrogen bonding and flexibility do not significantly contribute to the differential UV absorption between dsDNA and ssDNA.