DNA Gel Electrophoresis: Analyzing Genetic Fragments

DNA gel electrophoresis is a common molecular biology technique used for separating and analyzing DNA fragments based on their sizes. The process involves loading different-sized DNA fragments onto a gel made of agarose, a carbohydrate found in red algae.

Preparing and casting the agarose gel

  1. Dissolve agarose in an appropriate amount of electrophoresis buffer. The concentration of the gel is determined by the mass-to-volume ratio, such as 1g of agarose in 100ml of buffer for a 1% gel.
  2. Heat the mixture in a microwave, rotating the container to ensure complete dissolution of agarose.
  3. Add ethidium bromide to the gel solution to a final concentration of 0.5mg/ ml. Ethidium bromide intercalates between adjacent DNA base pairs and emits orange fluorescence under UV light. Note that ethidium bromide is a carcinogen, so handling it requires proper safety measures like wearing gloves.
  4. Cool the gel solution in a water bath to prevent the gel tray from warping due to high temperatures.
  5. Place a comb into the gel solution to form sample wells. Select combs suitable for the amount of DNA sample you’ll be loading. Pour the agarose gel solution into the gel tray and allow it to solidify at room temperature.
  6. Once the gel has solidified, remove the comb. If you won’t be using the gel immediately, wrap it in plastic wrap and store it at 4℃ until needed.

Preparing and running the gel

Before starting the electrophoresis, mix the DNA sample with loading buffer. The loading buffer is usually six times more concentrated and helps the sample sink to the bottom of the wells and track the movement during electrophoresis.

Set the power supply to the specified voltage.

Add enough electrophoresis buffer to the gel tank to cover the gel’s surface. Ensure the correct electrode connections.

Load the DNA sample and molecular weight markers into the gel wells.

Turn on the power supply to initiate electrophoresis.

Observing separated DNA fragments

After electrophoresis, turn off the power supply and remove the gel.

Use a UV light source to illuminate the gel; DNA fragments will appear as orange fluorescent bands.

Document the gel image to analyze the separated DNA fragments.

After the experiment, ensure proper disposal of the gel and electrophoresis buffer, following laboratory guidelines. Always wear gloves when handling gels and buffers containing ethidium bromide to protect against exposure to this hazardous substance.

DNA gel electrophoresis is widely used in molecular biology and genetics research for estimating DNA molecule sizes, separating DNA fragments, detecting gene mutations, and DNA fingerprinting, among other applications. It is a simple and effective experimental technique that helps in understanding the composition and characteristics of DNA samples.

Beijing Liuyi Biotechnology Co.Ltd, a professional manufacturer focusing on electrophoresis products over 50 years, offers a range of electrophoresis tanks (chambers/cells) for gel electrophoresis, such as horizontal electrophoresis tanks (chambers/cells) for DNA gel electrophoresis, and vertical electrophoresis tanks (chambers/cells) for protein gel electrophoresis. Meanwhile, it also provides different types of electrophoresis power supply, cabinet dark box analyzer and UV transilluminator. You can choose Beijing Liuyi’s electrophoresis tanks (chambers/cells) to measure the molecular weight of RNA and to separate RNA of different sizes for your lab.

Here we will recommend one type of horizontal electrophoresis tank (chamber/cell) model DYCP-31DN to make and run the gel.


After running the gel, you can use our gel image & analysis system model WD-9413B to observe, analyze and take pictures for the gel. Liuyi Biotech also offers UV transilluminator (UV Analyzer) to observe the gel. We have black-box type UV transilluminator (UV Analyzer) model WD-9403A9403CWD-9403F, portable UV transilluminator (UV Analyzer) model WD-9403B and handhold UV transilluminator (UV Analyzer) WD-9403E for you choose.


The Beijing Liuyi brand has more than 50-year history in China and the company can provide stable and high-quality products all around the world. Through years of development, it is worthy of your choice!

We are now looking for partners, both OEM electrophoresis tank and distributors are welcomed.

If you have any purchasing plan for our products, please don’t hesitate to contact us. You can send us message at email [email protected] or [email protected], or please call us at +86 15810650221 or add Whatsapp +86 15810650221, or Wechat: 15810650221.

Post time: Aug-08-2023