DNA Hybridization

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In 1960, Julius Marmur and his coworkers conducted studies at Harvard University
that resulted in the discovery of the process of reannealing. This process involves the
reassociation of single strands into double-stranded molecules that are stable. From the
discovery of the reannealing process, the methodology nucleic acid hybridization has
evolved. Using this technique, strands of nucleic acids that are both complementary and
from different sources can be mixed to form double-stranded molecules which are labeled
"hybrid" (Karp 429). Since its development, nucleic acid hybridization has branched into
several different techniques and is used for a variety of purposes.
There are a variety of purposes that can be fulfilled by nucleic acid hybridization. For example, a particular DNA probe (pDT1720) can be used to detect the presence of Campylobacter jejuni in food samples (Kingombe 4558). This probe, a particular nucleic acid, functions to identify DNA strands which are complementary to itself in sequence (Karcher 269). Also, "in situ hybridization" has been developed to detect the location of satellite DNA. In this method, the DNA of the chromosomes is held in place to allow it to react with a certain DNA (Karp 432).
One of the most useful of the purposes, however, is the use of DNA hybridization as a comparison technique which uses complementary base pairing to compare the genomes of two different species and evaluate the similarities between them. In this process, the DNA helices from two different species are unwound and mixed. The rate in which the hybrid DNA double helices is measured because the faster that hybrids (those double-stranded DNA molecules containing a strand from each species) form, the stronger the relationship between the two species. Below is a diagram which explains why humans are more closely related to chimpanzees than to chickens.
This type of study is important in...