1. What is DNA Oligo Molecular Weight?

The molecular weight of a DNA oligonucleotide is the sum of the molecular weights of its constituent nucleotides plus one water molecule. It's essential for various molecular biology applications including PCR, sequencing, and hybridization experiments.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( MW \) — Molecular weight (g/mol)
• \( N_i \) — Count of each nucleotide
• \( MW_i \) — Molecular weight of each nucleotide (g/mol)
• 18.02 — Molecular weight of water (g/mol)

Nucleotide Weights:

• Adenine (A): 313.21 g/mol
• Thymine (T): 304.20 g/mol
• Cytosine (C): 289.18 g/mol
• Guanine (G): 329.21 g/mol

3. Importance of Molecular Weight Calculation

Details: Knowing the molecular weight is crucial for preparing solutions with specific molar concentrations, calculating extinction coefficients, and designing experiments with precise DNA quantities.

4. Using the Calculator

Tips: Enter the DNA sequence (case insensitive, only ATCG characters are considered). The calculator will provide the molecular weight in g/mol and nucleotide counts.

5. Frequently Asked Questions (FAQ)

Q1: Why is water added to the calculation?
A: The water molecule accounts for the hydroxyl group at the 3' end and the hydrogen at the 5' end of the oligonucleotide.

Q2: Does this work for modified nucleotides?
A: No, this calculator only works for standard A, T, C, G nucleotides. Modified bases require special calculations.

Q3: How accurate is this calculation?
A: It provides theoretical molecular weight based on average nucleotide masses. For precise work, consider using mass spectrometry.

Q4: What about double-stranded DNA?
A: This calculator is for single-stranded oligonucleotides. For dsDNA, multiply by 2 and subtract the molecular weight of one water molecule.

Q5: Can I use lowercase letters?
A: Yes, the calculator automatically converts to uppercase and ignores non-ATCG characters.