Experimental analysis of nucleic acids: Which routine property is most commonly measured to analyze and quantify DNA or RNA in the laboratory?

Introduction / Context:
Every molecular biology lab relies on rapid methods to assess nucleic acids. Spectrophotometric absorbance is the standard first-line tool for concentration and purity assessment of DNA/RNA samples.

Given Data / Assumptions:

• Nucleic acids contain conjugated double bonds in bases that absorb ultraviolet light.
• Typical instruments measure absorbance at 260 nm and 280 nm.
• We seek the most common/straightforward analytical readout.

Concept / Approach:
Nucleic acids exhibit strong absorbance at 260 nm. The A260 value is used for concentration (using standard conversion factors), while A260/A280 and A260/A230 ratios estimate purity. Visible-light absorbance is minimal for pure nucleic acids, and determining molecular weight usually requires gels or advanced instrumentation rather than quick spectrophotometry.

Step-by-Step Solution:
Recognize that nucleic acid bases absorb UV light at ~260 nm.Use A260 for concentration; use A260/A280 for protein contamination checks.Therefore, “absorption of uv light” best matches routine analysis.

Verification / Alternative check:
Nanodrop and cuvette spectrophotometers standardize A260 reads for DNA/RNA quantification.

Why Other Options Are Wrong:

• Molecular weight: commonly determined by electrophoresis, not the quickest routine metric.
• Visible light absorption: nucleic acids have little absorbance in the visible range.
• None of these: incorrect since UV absorbance is widely used.

Common Pitfalls:
Interfering contaminants (phenol, guanidine) can skew A260/A280; interpret ratios with care.

Final Answer:
absorption of uv light