1. What is DNA Molecular Weight?

The molecular weight (MW) of DNA is calculated based on its length in base pairs. The NEB (New England Biolabs) approximation uses 650 g/mol per base pair for double-stranded DNA.

2. How Does the Calculator Work?

The calculator uses the NEB DNA MW formula:

Where:

• \( MW \) — Molecular weight (g/mol)
• \( L \) — Length of DNA in base pairs
• 650 — Average molecular weight per base pair (g/mol)

Explanation: This is an approximation that works well for standard double-stranded DNA. The actual MW may vary slightly depending on base composition.

3. Importance of DNA MW Calculation

Details: Knowing the molecular weight of DNA is essential for molecular biology applications like PCR, gel electrophoresis, and DNA quantification.

4. Using the Calculator

Tips: Enter the length of your DNA fragment in base pairs. The value must be a positive integer (1 or greater).

5. Frequently Asked Questions (FAQ)

Q1: Why use 650 g/mol per base pair?
A: This is the average molecular weight used by NEB for quick calculations, accounting for both strands and the sodium salt form of DNA.

Q2: How accurate is this calculation?
A: It's an approximation. The exact MW depends on base composition (A-T pairs are lighter than G-C pairs).

Q3: Does this work for single-stranded DNA?
A: No, for single-stranded DNA you should use approximately 330 g/mol per nucleotide.

Q4: What about RNA molecular weight?
A: RNA calculations are different - use approximately 340 g/mol per nucleotide for single-stranded RNA.

Q5: When would I need exact molecular weight?
A: For most applications the approximation is sufficient, but for precise molar calculations (like cloning) you may need exact MW based on sequence.