DNA Copy Number Calculator
Determine the exact number of DNA molecules in your tube. This calculator uses Avogadro's number to bridge the gap between mass and molecular count.
Number of Copies = (Amount of DNA in ng × 6.022 × 10²³) / (Length in bp × 10⁹ × 660)
Where:
• Amount of DNA: Your sample mass in nanograms.
• Length: Total length of the DNA fragment in base pairs.
• 6.022 × 10²³: Avogadro's Number (molecules per mole).
• 660 g/mol: Average molecular weight of one double-stranded DNA base pair.
Scenario: You have 100 ng of a plasmid that is 4,000 base pairs (bp) long and need to find the absolute number of molecules.
Calculation:
1. Mass in grams = 100 × 10⁻⁹.
2. Molar mass of plasmid = 4,000 × 660 = 2,640,000 g/mol.
3. Moles = (100 × 10⁻⁹) / 2,640,000 ≈ 3.78 × 10⁻¹⁴ moles.
4. Copies = Moles × Avogadro's Number ≈ 2.28 × 10¹⁰ molecules.
Result: The sample contains approximately 22.8 billion DNA copies.
What is DNA copy number?
DNA copy number refers to the total number of molecules of a specific DNA sequence (such as a plasmid or genome) present in a sample.
How do I calculate the number of DNA copies?
The formula is: Number of copies = (Amount of DNA in nanograms × Avogadro's constant) / (Length of DNA in base pairs × average weight of one base pair).
What is the average weight of a DNA base pair?
The average weight of one double-stranded DNA base pair (bp) is approximately 660 Daltons (g/mol).
Why is Avogadro's constant used?
Avogadro's constant (6.022 × 10²³) represents the number of molecules in one mole of a substance, allowing us to convert between mass and the actual number of molecules.
🔗 Related Calculators
📐 Formula
Number of Copies = (Amount of DNA in ng × 6.022 × 10²³) / (Length in bp × 10⁹ × 660)
Where:
• Amount of DNA: Your sample mass in nanograms.
• Length: Total length of the DNA fragment in base pairs.
• 6.022 × 10²³: Avogadro's Number (molecules per mole).
• 660 g/mol: Average molecular weight of one double-stranded DNA base pair.
📝 Example Calculation
Scenario: You have 100 ng of a plasmid that is 4,000 base pairs (bp) long and need to find the absolute number of molecules.
Calculation:
1. Mass in grams = 100 × 10⁻⁹.
2. Molar mass of plasmid = 4,000 × 660 = 2,640,000 g/mol.
3. Moles = (100 × 10⁻⁹) / 2,640,000 ≈ 3.78 × 10⁻¹⁴ moles.
4. Copies = Moles × Avogadro's Number ≈ 2.28 × 10¹⁰ molecules.
Result: The sample contains approximately 22.8 billion DNA copies.
❓ Frequently Asked Questions
What is DNA copy number?▼
DNA copy number refers to the total number of molecules of a specific DNA sequence (such as a plasmid or genome) present in a sample.
How do I calculate the number of DNA copies?▼
The formula is: Number of copies = (Amount of DNA in nanograms × Avogadro's constant) / (Length of DNA in base pairs × average weight of one base pair).
What is the average weight of a DNA base pair?▼
The average weight of one double-stranded DNA base pair (bp) is approximately 660 Daltons (g/mol).
Why is Avogadro's constant used?▼
Avogadro's constant (6.022 × 10²³) represents the number of molecules in one mole of a substance, allowing us to convert between mass and the actual number of molecules.