1. What is the Copy Number Formula?

The copy number formula calculates the number of DNA molecules in a given volume based on concentration, length, and Avogadro's number. It's essential for molecular biology applications like PCR, qPCR, and sequencing.

2. How Does the Calculator Work?

The calculator uses the copy number formula:

Where:

• \( CN \) — Copy number (dimensionless)
• \( C \) — DNA concentration (ng/μL)
• \( L \) — DNA length (base pairs)
• \( 6.022 \times 10^{23} \) — Avogadro's number (molecules/mol)
• \( 650 \) — Average molecular weight per base pair (g/mol)

Explanation: The formula converts mass concentration to molar concentration, then calculates the number of molecules using Avogadro's number.

3. Importance of Copy Number Calculation

Details: Accurate copy number determination is crucial for PCR setup, standard curve generation, NGS library quantification, and ensuring experimental reproducibility.

4. Using the Calculator

Tips: Enter DNA concentration in ng/μL and length in base pairs. For best results, use accurate spectrophotometric or fluorometric concentration measurements.

5. Frequently Asked Questions (FAQ)

Q1: Why is 650 used in the formula?
A: 650 g/mol is the average molecular weight of a DNA base pair (including both nucleotides and counterions).

Q2: What concentration range works best?
A: The formula works for any concentration, but typical working concentrations range from 0.1-100 ng/μL for most molecular biology applications.

Q3: Does this work for RNA?
A: No, for RNA you would need to use the average molecular weight of an RNA nucleotide (340 g/mol) and adjust the formula accordingly.

Q4: How accurate is this calculation?
A: The calculation is mathematically precise, but accuracy depends on the precision of your concentration measurement and the actual base composition of your DNA.

Q5: Can I use this for plasmid copy number?
A: Yes, but remember this calculates absolute copy number in your sample, not relative plasmid copy number in bacterial cells.