1. What is DNA Molecular Weight?

The molecular weight (MW) of DNA is the sum of the atomic weights of all atoms in the DNA molecule. It's typically expressed in g/mol (grams per mole) and is important for many molecular biology applications.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• \( A \) — Count of Adenine bases
• \( T \) — Count of Thymine bases
• \( C \) — Count of Cytosine bases
• \( G \) — Count of Guanine bases
• 313 — MW of Adenine monophosphate (g/mol)
• 304 — MW of Thymine monophosphate (g/mol)
• 289 — MW of Cytosine monophosphate (g/mol)
• 329 — MW of Guanine monophosphate (g/mol)
• 61 — Adjustment for single phosphate group

Explanation: The formula calculates the sum of nucleotide monophosphates minus one water molecule (18 g/mol) and one proton (1 g/mol) per phosphodiester bond.

3. Importance of DNA MW Calculation

Details: Knowing DNA molecular weight is crucial for PCR primer design, DNA quantification, electrophoresis, and many other molecular biology techniques.

4. Using the Calculator

Tips: Enter counts for each nucleotide (A, T, C, G) and select whether it's single-stranded or double-stranded DNA. All values must be non-negative integers.

5. Frequently Asked Questions (FAQ)

Q1: Why are the values different for each base?
A: Each nucleotide has a different molecular weight due to their unique chemical structures.

Q2: How does double-stranded DNA affect the calculation?
A: For dsDNA, the molecular weight is simply doubled since it contains two complementary strands.

Q3: Does this account for modified bases?
A: No, this calculator only works for standard DNA bases (A, T, C, G). Modified bases require special calculations.

Q4: What about RNA molecular weight?
A: RNA uses uracil (U) instead of thymine, with a different molecular weight (306 g/mol for UMP).

Q5: How accurate is this calculation?
A: It provides a theoretical MW based on average isotopic composition. Actual MW may vary slightly due to isotopic distributions.