Showing posts with label Lab Methods. Show all posts
Showing posts with label Lab Methods. Show all posts

Thursday 15 August 2024

New Video Posted: Bacterial Transformation: Natural vs. Artificial Methods Explained

In this video - Bacterial Transformation: Natural vs. Artificial Methods Explained - I look at how bacteria can take up DNA from the environment and how we can get bacteria to take up DNA in the lab.


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

Bacterial transformation is where bacteria take up external DNA, which can lead to genetic changes within the cell. This process can occur naturally or be induced artificially in a laboratory setting. 

Natural Transformation

In natural transformation, bacteria acquire DNA from their surroundings, typically from nearby bacteria that have lysed (broken apart). The free-floating DNA can then be integrated into the bacterial chromosome or replace an existing gene, leading to potential new traits or functions. This ability to naturally take up DNA is a trait of "competent" cells, which possess specific genes that encode the machinery necessary for DNA uptake.

Artificial Transformation 

In a lab, we can induce transformation using artificial methods. Unlike natural transformation, this process requires deliberate manipulation of the bacteria to make them more likely to accept new DNA. First, the bacteria must be made competent so they can take up the DNA. Techniques such as heat shock, electroporation, or polycations are then used to encourage bacteria to take up the DNA. Each method works differently but ultimately serves the same purpose: introducing new genetic material into bacterial cells, enabling researchers to study gene function, produce recombinant proteins, or create genetically modified organisms.

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

Friday 3 May 2024

New video posted: Understanding Nucleic Acid Hybridisation: Methods & Applications Explained

In this video, I look at Nucleic Acid Hybridisation and how it is the underlying principle for several lab techniques, such as PCR (Polymerase Chain Reaction), dot blots, colony blot hybridisation, chromosome in situ hybridisation (FISH), microarrays, Southern and Northern blotting, and CRISPR/Cas9 gene editing.

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 defining the key terms - download.

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.

DNA gel showing a DNA ladder and a band

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.

Agarose gel showing the DNA ladder and the band of unknown size, plus a table of data constructed from the gel for the grapg

From the table, you plot the calibration curve.

Calibration curve for determining the size of a band on a DNA gel

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.