Agarose gel electrophoresis is the technique employed to check the progression of a restriction enzyme digestion in recombinant DNA technology.

Agarose gel electrophoresis:
Agarose gel electrophoresis is a widely used technique in molecular biology and recombinant DNA technology. It is used to separate and analyze DNA fragments based on their size. Agarose, a polysaccharide extracted from seaweed, is used to create a gel matrix through which the DNA molecules can migrate.

Procedure:
1. Preparation of gel: Agarose powder is mixed with a buffer solution and heated to form a gel. The gel is poured into a casting tray and allowed to solidify.

2. Sample preparation: The DNA samples to be analyzed are mixed with a loading dye, which contains a tracking dye and a denser substance that makes the DNA sample sink into the well of the gel.

3. Loading the gel: The gel is placed in a horizontal electrophoresis chamber filled with an electrophoresis buffer. The DNA samples are loaded into wells made at one end of the gel.

4. Electrophoresis: An electric current is applied across the gel, causing the negatively charged DNA molecules to migrate towards the positive electrode. The smaller DNA fragments move faster through the gel than larger fragments.

5. Visualization: After electrophoresis, the DNA fragments are stained with a fluorescent dye, such as ethidium bromide, which binds to the DNA and fluoresces under UV light. The gel is then placed under UV light, and the DNA bands can be visualized and photographed.

Progression of a restriction enzyme digestion:
In recombinant DNA technology, restriction enzymes are used to cut DNA at specific recognition sites. After carrying out a restriction enzyme digestion, agarose gel electrophoresis is used to check the progression of the digestion.

1. Digestion reaction: The DNA sample is mixed with the appropriate restriction enzyme and buffer, and the digestion reaction is carried out under specific conditions.

2. Loading the gel: The digested DNA samples are mixed with loading dye and loaded into the wells of the gel.

3. Electrophoresis: The gel is subjected to electrophoresis, and the DNA fragments migrate through the gel based on their size. Uncut DNA will remain as a single band, while digested DNA will show multiple bands representing the different fragment sizes.

4. Visualization: After electrophoresis, the gel is stained and visualized under UV light. The presence of distinct bands indicates successful digestion, while the absence of bands or the presence of a single band suggests incomplete or no digestion.

By analyzing the band pattern obtained from agarose gel electrophoresis, researchers can determine the success and progress of the restriction enzyme digestion in recombinant DNA technology.