FREE ESSAY ON DNA GEL ELECTROPHOROSIS

DNA GEL ELECTROPHOROSIS

Introduction:
DNA, Deoxyribonucleic acid, is a double stranded, helical nucleic 
acid molecule which determines inherited structure of a protein. The 
"steps" are made of bases: adenine, guanine, cytosine, and thymine. The 
sides are sugar and phosphate molecules. Restriction enzymes are 
enzymes that cut DNA at restriction sites, leaving fragments blunt or 
sticky. The restriction fragments are separated using a technique called 
gel electrophoresis. 
DNA has a negative charge so when an electrical charge is 
applied it makes DNA move to the positive side. DNA is placed in 
agarose gel. Smaller fragments move faster. The purpose of this lab is to 
separate DNA fragments using gel electrophoresis. Hind III cuts AAGCTT 
between the two irst A's. EcoRI cuts at GAATTC between the G and the 
A. Hind III and EcoRI both make sticky ends.
Results:
Our results for this lab were EcoRI separated into five fragments. 
Hind III separated into four fragments. The control only had one fragment. 
(See chart A and figure 1-1 for distances) 
Discussion: 
The purpose of this lab was to see how gel electrophoresis 
separates DNA fragments. We used Hind III, EcoRI, and a controlled 
enzyme. Some fragments were hard to see because of smearing. These 
were the bigger fragments. Loading the DNA was difficult and if you 
weren't careful you could rupture the wells which ruined the lab. We, 
fortunately, did not run into this problem.
Abstract:
The purpose of this lab is to separate DNA fragments with gel 
electrophoresis using EcoRI and Hind III. Restriction enzymes are used to 
break up the DNA, then negatively charged DNA is placed in a gel 
casting tray. Then it is placed into an electrophoresis chamber. An 
electrical field is placed across the agarose gel which forces the 
fragments to move down the gel. The amount of lines show how many 
fragments there is in the DNA. We had five fragments for EcoRI and six 
for Hind III. The no enzyme had only one fragment.
Procedures: 
We sealed the ends of a gel casting tray with masking tape and 
inserted a comb into the slots. The tray was filled about 6mm high with 
agarose gel. It covered half the height of the comb. We waited ten 
minutes for the gel to solidify. Then we placed the tray in a gel box and 
made sure that the comb was at a negative (black) end. The box was 
filled with tris-borate-EDTA buffer so it covered the entire surface of the 
gel. The combs were removed without ripping the wells. The micro pipet 
was used to load the lambda EcoRI, lambda Hind III, and lambda only 
into the wells. We dipped the pipet trough the surface of the buffer over 
the wells and expelled the contents. The top of the electrophoresis 
chamber was closed and electrical leads were connected. The dye was 
observed as it moved shortly after the power supply was turned on. The 
power supply was turned off after the bands migrated near the end of 
the gel and the top of the electrophoresis chamber was removed. We 
removed the gel from the gel casting tray and examined it under a light 
box and compared it to the ideal gel (figure1-2).
Bibliography
References:
Restriction Enzymes: Cleavage of DNA lab 
University of Illinois. (1999). Experiment 2
Gel Electrophoresis of DNA. In 
Molecular Biology Cyberlab, online: 
Http://www.life.uluc.edu/molbio/geldigest/electro.html