Molecular Biology is the study of the structure and function of molecules essential to life. Scientists have many tools to study the role of RNA, DNA, and proteins in cell function. Here are a few.

NHS National Genetics and Genomics Education Centre

NHS National Genetics and Genomics Education Centre

http://www.discoveryandinnovation.com/BIOL202/notes/images/gelbox.jpg

http://www.discoveryandinnovation.com/BIOL202/notes/images/gelbox.jpg

Gel Electrophoresis - While DNA and RNA are large molecules, they are still barely perceptible to the human eye. In order to visualize and measure their size, scientist use an electric field run over a gel slab filled with different samples of interest. The gel consists of a 1-2% agarose solution microwaved and buffer. This polymer is very nonreactive. In addition, the pores formed when cooling are aid in the separation of large molecules. A "comb" is inserted toward the top of one side of the mold to create places to load samples.

Before the gel is allowed to cool and harden, ethidium bromide is frequently added. This substance enables visualization of the DNA with UV light, but is a known mutagen (the kind that gives you cancer, not superpowers). When ready place the gel in the center of the box and pour in a running buffer (either Tris-acetate EDTA, TAE, or Tris-borate EDTA, TBE) until it is just fully submerged. On the far left lane load your "ladder", a dye mixed with DNA fragments of known length. The ultimate position of molecules in the gel will depend on the strength and duration of the electric field. The ladder allows you to determine the size of your samples through comparison. While not necessary, addition of a dye to your samples can help with loading and knowing when sufficient time has passed. When ready close the box and attach the electrodes. The wires are usually color coded, but make sure the top of the gel is black (-) and the bottom is red (+). Remember, always "Run-to-Red" otherwise your samples will go backwards and fall off the gel within a few minutes.  

At the end, turn of the power supply and carefully remove the gel. Wear a UV face shield, place the gel on a UV light box, and take a picture. Do not stare at the light box without at least eye protection. Extended use of a light box can lead to sunburn of exposed skin if you don't have the right protective gear. Correctly dispose of the gel, particularly if you used ethidium bromide.

 

By TransControl (GFDL ), via Wikimedia Commons

By TransControl (GFDL ), via Wikimedia Commons

Classroom: The hardware for running these experiments is fairly affordable. An introductory kit will run you a few hundred dollars and the hardware should last quite awhile. Different reagents can be purchased to refill the starting materials or change the demonstration. For example, a mystery can be set up to let the students test their forensic skills.