1. What is DNA Copy Number?

DNA copy number refers to the number of copies of a particular DNA molecule present in a sample. It's calculated based on the amount of DNA (in nanograms) and the length of the DNA molecule (in base pairs).

2. How Does the Calculator Work?

The calculator uses the DNA copy number formula:

Where:

• \( ng \) — Amount of DNA in nanograms
• \( bp \) — Length of DNA in base pairs
• \( 6.022 \times 10^{23} \) — Avogadro's number (molecules per mole)
• \( 660 \) — Average molecular weight of one DNA base pair (g/mol)

Explanation: The formula converts the mass of DNA to molar quantity, then calculates the number of individual molecules based on the length of the DNA.

3. Importance of DNA Copy Number

Details: Knowing the exact copy number is crucial for molecular biology applications like qPCR, sequencing library preparation, and genetic engineering where precise DNA quantities are required.

4. Using the Calculator

Tips: Enter the DNA amount in nanograms and the DNA length in base pairs. Both values must be positive numbers (length must be at least 1 bp).

5. Frequently Asked Questions (FAQ)

Q1: Why is 660 g/mol used for DNA base pairs?
A: This is the average molecular weight of a DNA base pair, accounting for different nucleotide compositions.

Q2: Does this work for single-stranded DNA?
A: No, this calculator is specifically for double-stranded DNA. For ssDNA, you would need to adjust the molecular weight.

Q3: How accurate is this calculation?
A: It provides a theoretical estimate. Actual copy numbers may vary slightly due to measurement errors and DNA purity.

Q4: Can I use this for RNA?
A: No, RNA has a different molecular weight. A separate calculation would be needed for RNA molecules.

Q5: What's a typical copy number range for PCR?
A: Most qPCR reactions use between 1,000 and 1,000,000 copies as template, depending on the application.