New Video Posted: How to Calculate the Gradient (m) and Intercept (c) in y = mx + c | Gel Analysis Tutorial

This video is in response to a question I have received on YouTube:

“Thanks it is very helpful but can you present how to calculate slope and intercept in this curve”

The question often gets asked about two of my other videos:

• How to calculate the size of a DNA band on a gel?
• How to Determine Protein Size on an SDS-PAGE Gel | Step-by-Step Tutorial

In the How to Calculate the Gradient (m) and Intercept (c) in y = mx + c | Gel Analysis Tutorial, I explain how to calculate the gradient (m) and intercept (c) in the linear equation y = mx + c. I explain three methods that can be used:

1. Graph-based calculation
2. Solving simultaneous equations
3. Using Excel or Apple Numbers.

In the video, I use DNA gel data to illustrate these calculations.

If you would like to say thanks for the video, then please feel free to buy me a coffee at https://www.buymeacoffee.com/drnickm

Blog Bonus: Free information sheet summarising the video and defining the key terms - download.

Additional Resources

• 📗 - Maths and Chemistry Refresher for Life and Biomedical Scientists
• 📗 - Catchup Chemistry (affiliate link to the book)
• 📗 - Catchup Maths and Stats (affiliate link to the book)

New eBook Available: Maths and Chemistry Refresher for Life and Biomedical Scientists

I have a new eBook available on Google Play Books - Maths and Chemistry Refresher for Life and Biomedical Scientists.

Maths and Chemistry Refresher
for Life and Biomedical Scientists

The book is a refresher for life, biomedical sciences and chemistry students who may be a little unsure of some of the key maths and chemistry skill they need and covers:

• Elements, atoms, ions, molecules, and compounds
• Atomic weight, isotopes and molecular weight
• Amounts, volumes, and concentrations
• The SI units and the SI unit prefixes (m, µ, n, p etc.)
• Scientific Notation
• Dealing with unit prefixes (m, µ, n, p etc.) in calculations 
• Order of operations (BODMAS and PEMDAS) in maths
• How to get the best out of your calculator
• Maths 'tricks' — Logs
• And, graphs

A Comprehensive Guide on How to Calculate the Size of a DNA Band on a Gel

How do scientists determine the size of DNA bands on an agarose gel? In this guide, I will walk you through the step-by-step process of calculating the size in base pairs of a DNA band on an agarose gel. 

Blog Bonus: Free information sheet summarising the video and the steps - download.

 

Introduction

When working in a lab and running an agarose gel, you may need to determine the size of the DNA fragment, and this information may be crucial for various biological research applications. 

This approach is also described in the following video:

Setting Up the Experiment

Imagine you have loaded a DNA ladder with known sizes in one lane and your DNA sample with an unknown size in another lane of the gel and you get a result that looks like this when the gel has been run.

Before you can calculate the size of your DNA band, you must first label the gel and collect data to create a calibration curve.

Data Collection and Analysis

By measuring the distances the DNA bands in the ladder (see below) have moved and plotting the log values of their sizes against the distances travelled in millimetres (or you can do it in pixels), you can create a calibration curve. This curve will help you accurately determine the size of the DNA band in your unknown sample.

The image below shows the gel and the data table for the plot.

From the table, you plot the calibration curve.

Calculating the Size of the DNA Band

After plotting the calibration curve (above) and identifying the distance your unknown band has travelled, you can use the curve to determine the size of the DNA band in base pairs. By following a simple formula involving logarithms, you can convert the log value to the actual size in base pairs.

Conclusion

Calculating the size of a DNA band on an agarose gel requires careful data collection, analysis, and interpretation. By following the steps outlined in this guide, you can confidently determine the size of DNA fragments in your samples. 

If you would like to support my blogging efforts, then please feel free to buy me a coffee at https://www.buymeacoffee.com/drnickm

Blog Bonus: Free information sheet summarising the video and the steps - download.

Additional Resources

• 📗 - Maths and Chemistry Refresher for Life and Biomedical Scientists
• 📗 - Catchup Chemistry (affiliate link to the book)
• 📗 - Catchup Maths and Stats (affiliate link to the book)