1. What is Nucleic Acid Molecular Weight?

The molecular weight (MW) of a nucleic acid is the sum of the atomic weights of all atoms in the molecule. For DNA or RNA, it's calculated by summing the molecular weights of individual nucleotides plus any modifications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( base\_masses \) — Molecular weights of individual nucleotides (g/mol)
• DNA bases: A (313.21), T (304.2), C (289.18), G (329.21)
• RNA bases: A (329.21), U (306.17), C (305.18), G (345.21)
• Modifications: 5' Phosphate (+79.0), 3' OH (+17.01)

Explanation: The calculator sums the molecular weights of each base in the sequence and adds any modification weights.

3. Importance of Molecular Weight Calculation

Details: Knowing the molecular weight is essential for preparing solutions with specific molar concentrations, PCR primer design, and various molecular biology applications.

4. Using the Calculator

Tips: Enter the nucleic acid sequence (A,T,C,G for DNA; A,U,C,G for RNA), select the type (DNA/RNA), and any modifications. The sequence is case-insensitive.

5. Frequently Asked Questions (FAQ)

Q1: Does this include water molecules lost during polymerization?
A: Yes, the molecular weights already account for the loss of water during phosphodiester bond formation.

Q2: How accurate is this calculation?
A: It provides a theoretical molecular weight based on average isotopic composition. For exact mass, isotopic distribution must be considered.

Q3: What about modified bases?
A: This calculator handles only 5' phosphate and 3' OH modifications. For other modifications, specialized calculators should be used.

Q4: Why are DNA and RNA base weights different?
A: RNA contains uracil (U) instead of thymine (T) and has an extra hydroxyl group on the ribose sugar.

Q5: Can I calculate molecular weight for both strands of DNA?
A: This calculator computes single-strand MW. For double-stranded DNA, multiply by 2 and subtract for any overhangs.