1. What is DNA Molecular Weight?

The molecular weight of a DNA strand is the sum of the molecular weights of its constituent nucleotides. It's an important parameter in DNA extraction protocols, PCR setup, and other molecular biology applications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( MW \) — Molecular weight of DNA strand (g/mol)
• \( MW_{nuc} \) — Molecular weight of individual nucleotides (g/mol)
• A = 313.21 g/mol
• C = 289.18 g/mol
• G = 329.21 g/mol
• T = 304.20 g/mol

Explanation: The calculator sums the molecular weights of all nucleotides in the sequence, adds the 5' phosphate group, and adjusts for double-stranded DNA if selected.

3. Importance of Molecular Weight Calculation

Details: Knowing the molecular weight is essential for:

• Determining DNA concentration
• Calculating molar ratios for PCR
• Setting up restriction digests
• Designing cloning experiments

4. Using the Calculator

Tips: Enter the DNA sequence (ACGT only, case insensitive) and select whether it's single- or double-stranded. The calculator will compute the molecular weight in g/mol.

5. Frequently Asked Questions (FAQ)

Q1: Why is the molecular weight important in DNA extraction?
A: It helps determine DNA concentration and purity, which are critical for downstream applications.

Q2: How accurate is this calculator?
A: It provides theoretical molecular weight based on average nucleotide masses. For precise work, consider using mass spectrometry.

Q3: Does it account for modified bases?
A: No, this calculator only handles standard A, C, G, T nucleotides.

Q4: Why is double-stranded DNA adjustment needed?
A: Double-stranded DNA has two complementary strands but lacks one phosphate group at each end where strands join.

Q5: Can I use this for RNA sequences?
A: No, RNA has different molecular weights for its nucleotides (U instead of T, and slightly different masses).