SC1130Wk10
SC1130 Survey of the Sciences
Week 10 Analysis
DNA Evidence
Frank Bavone
5-4-15
In order to apprehend a criminal the first steps involve evidence collection. CSI technicians collect blood samples either by submitting a piece of clothing or by using a sterile cloth and a small amount of distilled water to remove some blood from the body as well as collect blood samples by scraping trace blood spatter from walls and floors into a sterile container using a scalpel. Blood samples are also collected from the body. These samples are then sent to be analyzed to determine if the samples are the same since any blood at the crime scene may belong to either the victim or assailant. The lab will perform DNA analysis on the sample as well as the victim to determine whether or not it can be used later to compare to blood taken from all suspects.
Once the blood sample is isolated from all other organic material DNA is extracted from its biological source material using a hypotonic chemical buffer and being centrifuged. The extracted DNA is then measured to evaluate the quantity. After isolating the DNA, specific regions are copied with a technique known as the polymerase chain reaction, or PCR. PCR produces millions of copies for each DNA segment of interest and thus permits very minute amounts of DNA to be examined. The resulting PCR products are then separated. The separation methods used today include slab gel and capillary electrophoresis. Fluorescence detection methods have greatly aided the sensitivity and ease of measuring PCR-amplified samples. The specific methods used for DNA typing are validated by individual laboratories to ensure that reliable results are obtained and before new technologies are implemented. Samples are then compared to each other as well as DNA databases which are a valuable tool and play an important role in apprehending criminals that have committed a crime before.
Resources
Ghatak, S., Muthukumaran, R. Nachimuthu,
Week 10 Analysis
DNA Evidence
Frank Bavone
5-4-15
In order to apprehend a criminal the first steps involve evidence collection. CSI technicians collect blood samples either by submitting a piece of clothing or by using a sterile cloth and a small amount of distilled water to remove some blood from the body as well as collect blood samples by scraping trace blood spatter from walls and floors into a sterile container using a scalpel. Blood samples are also collected from the body. These samples are then sent to be analyzed to determine if the samples are the same since any blood at the crime scene may belong to either the victim or assailant. The lab will perform DNA analysis on the sample as well as the victim to determine whether or not it can be used later to compare to blood taken from all suspects.
Once the blood sample is isolated from all other organic material DNA is extracted from its biological source material using a hypotonic chemical buffer and being centrifuged. The extracted DNA is then measured to evaluate the quantity. After isolating the DNA, specific regions are copied with a technique known as the polymerase chain reaction, or PCR. PCR produces millions of copies for each DNA segment of interest and thus permits very minute amounts of DNA to be examined. The resulting PCR products are then separated. The separation methods used today include slab gel and capillary electrophoresis. Fluorescence detection methods have greatly aided the sensitivity and ease of measuring PCR-amplified samples. The specific methods used for DNA typing are validated by individual laboratories to ensure that reliable results are obtained and before new technologies are implemented. Samples are then compared to each other as well as DNA databases which are a valuable tool and play an important role in apprehending criminals that have committed a crime before.
Resources
Ghatak, S., Muthukumaran, R. Nachimuthu,