In our next lab we will be comparing band patterns produced by restriction enzyme cleavage of DNA samples. Restriction enzymes are enzymes that move down the helix until it recognizes specific sequences of base pairs that tell the enzyme to stop moving. Then the enzyme will cut or chemically separate the DNA molecules, this spot is called a restriction site. When DNA is being looked at to compare, as if on a crime scene, the way you tell the difference between two different suspects is by looking at their DNA samples. Each persons DNA is "cut" differently by the restriction enzymes, in different fragments of size and length.The DNA can be observed by using agarose gel electrophoresis. Agarose Gel Electrophoresis separates DNA fragments by size when they are put in an "agarose gel slab" and then put into a separate tube with a buffer solution. The DNA fragments are negatively charged and when the agarose gel acts as a molecular sieve where only smaller DNA fragments will travel farther than larger ones. The fragments that are the same size will band together and we will see them when we finish our lab!
In a crime scene investigation to determine whose DNA is found, the DNA must be examined and you must look at its nucleotide sequence. Radioactive probes are what is used to locate, identify, and compare individuals DNA. DNA can be found form many different biological materials, such as, blood, hair and body tissues. the recognition plays a large part in today's crime scene investigations. In this lab we will learn the general bases for using DNA in modern times.
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