Biochemistry of DNA Fingerprinting
Since the 1980’s, DNA fingerprinting, also called DNA typing or DNA profiling, has been used to convict or release potential suspects in criminal investigations. DNA fingerprinting is also used in genetic counseling, childbirth decisions, and genealogy/ancestry. However, the use of these fingerprints is possibly the greatest tool used by criminal investigators.
DNA, deoxyribonucleic acid, is the blueprint the genetic makeup of a human being and exists in virtually every cell of the human body. DNA differs in the sequence of nucleotides (adenine, thymine, guanine, and cytosine), or variable number tandem repeats (VNTRs) in particular short tandem repeats (STRs). VNTRs can be inherited which can help trade the pattern or probability of a disease in a family. Individuals are extremely unlikely to have the same VNTRs; in fact, there is only a 1 in 64 billion chance that any 2 people would have comparable DNA. Comparable DNA does not even mean that the DNA is identical, it just means that the DNA is similar.
Fragments produced by various restriction enzymes can be used to identify individuals with the accuracy of a fingerprint. The commonly used methods for isolating and comparing genetic sequences include polymerase chain reactions (PCR) and restriction fragment length polymorphisms (RFLP). PCR is ideal for analyzing small amounts of DNA and the process involves a system of denaturing, annealing, and extending DNA. An increase of temperature triggers denaturing. The hydrogen bonds break between the double helix and they separate. In the process of annealing, the temperature is lowered, which enables primers to attach. Primers are segments of DNA that have a free OH group on the 3’ carbon of a nucleotide. These primers line up with specific sequences of amino acids. After the temperature is slightly increased, a DNA polymerase is able to attach nucleotides to the 3’ carbon of the primer and extend the complementary strand. Each temperature-regulated cycle greatly increases the amount of DNA present, which makes more available for amplification in the next cycle. After a lengthy process PCR strips can be viewed for analysis
Works Cited:
http://www.wiley.com/legacy/college/boyer/0470003790/cutting_edge/dna_fingerprinting/DNAFingr.htm
http://edusanjalbiochemist.blogspot.com/2013/06/dna-fingerprinting.html
https://www.youtube.com/watch?v=ZxWXCT9wVoI
When the hydrogen bonds break in the double helix, is there a release of hydrogen, of energy, or is nothing lost at all because of the law of conservation of mass and law of conversation of energy? If there is a release of energy, is that energy given off so that other bonds may break apart within the DNA? If there is not enough energy for the hydrogen bonds to break apart, how will energy be put into the double helix for the hydrogen bonds to break apart?
ReplyDeleteBerkley, when the hydrogen bonds break in the double helix, it is because of the enzymes known as DNA Helicases. These enzymes break the electrostatic hydrogen bonds between the two strands. This process requires energy, and according to the Law of Conservation of Energy, there has to be a release of energy. Since the hydrogen bonds are simply broken, there should not be a significant release of hydrogen gas, or an realize at all for that matter.
DeleteDoes the different in tandem repeats affect a person physical appear or just to provide the probability of receiving an inherit disease? How can VNTRs be use to identify an individual percent risk of receiving their parent genetic disease?
ReplyDelete