Which method would be most appropriate for measuring the size of DNA fragments?

The most appropriate method for measuring the size of DNA fragments is electrophoresis. This technique separates nucleic acids based on their size and charge by applying an electric field to a gel medium, typically agarose or polyacrylamide. Smaller DNA fragments migrate faster through the gel than larger ones, allowing for the determination of size by comparing the distance traveled to a set of known standards or ladders.

Electrophoresis provides a visual representation of DNA fragments, making it possible to assess their size accurately. The bands created after the electrophoresis run can be stained with fluorescent dyes or other chemical agents that bind to DNA, enabling visualization under UV light or other imaging systems.

In contrast, mass spectroscopy is typically used for analyzing small molecules or proteins rather than distinguishing DNA fragment sizes. Densitometry, while it can quantify the amount of substance in a sample, does not directly measure DNA fragment size. Turbidimetry measures the cloudiness or turbidity of a solution and is not suitable for determining the size of DNA fragments.