1. What is DNA Molecular Weight?

The molecular weight of a DNA sequence is the sum of the molecular weights of its nucleotides minus the molecular weight of water for each phosphodiester bond formed. It's essential for various molecular biology applications.

2. How Does the Calculator Work?

The calculator uses the DNA molecular weight formula:

Where:

• \( A \) — Count of adenine nucleotides
• \( T \) — Count of thymine nucleotides
• \( C \) — Count of cytosine nucleotides
• \( G \) — Count of guanine nucleotides
• 313.2 — Molecular weight of dAMP (g/mol)
• 304.2 — Molecular weight of dTMP (g/mol)
• 289.2 — Molecular weight of dCMP (g/mol)
• 329.2 — Molecular weight of dGMP (g/mol)
• 61.0 — Adjustment for water loss per bond

Explanation: The formula accounts for the molecular weights of individual nucleotides and the water molecules lost during phosphodiester bond formation.

3. Importance of Molecular Weight Calculation

Details: Knowing the molecular weight of DNA is crucial for PCR primer design, DNA quantification, electrophoresis, and various cloning techniques.

4. Using the Calculator

Tips: Enter the count of each nucleotide (A, T, C, G) in your DNA sequence. The counts must be non-negative integers.

5. Frequently Asked Questions (FAQ)

Q1: Does this calculator work for RNA sequences?
A: No, this calculator is for DNA only. RNA has uracil instead of thymine and slightly different molecular weights.

Q2: What about modified nucleotides?
A: This calculator uses standard nucleotide weights. Modified nucleotides would require different molecular weights.

Q3: Why subtract 61.0?
A: This accounts for the loss of water (H₂O, MW=18) during phosphodiester bond formation and the terminal phosphates (MW=61 total).

Q4: How accurate is this calculation?
A: It's accurate for standard DNA sequences. For precise work, consider using exact isotope masses.

Q5: Can I use this for oligonucleotides?
A: Yes, this works for any DNA sequence including short oligonucleotides.