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DNA Deoxyribonucleic acid or DNA, is a nucleic acid molecule that contains the hereditary information in humans and almost all other organisms. If you were to examine the cells in a person’s body, nearly all would have the same DNA. The main role of DNA is the long-term storage of information and this is stored as a code. The DNA segments that carry this genetic information are called genes.

DNA contains biological information that makes each species unique. That is why monkeys give birth only to baby monkeys and elephants only give birth to little elephants.

The spiral staircase-shaped double helix is the most common symbol for the DNA. It has an interesting twisting ladder structure.

The chemical structure of everyone's DNA is the same. There are millions of base pairs (a set of two bonded nucleotides on opposite strands of DNA) in each person’s DNA and it is the different sequence of the order of the base pair that amkes one person different from another. And you would be identified solely by the sequence of your base pair. For example, a sequence SDTRF represents different information than the sequence STDRF, just as SPIN has a different meaning from PINS. But given the millions of base pairs, this would be a Herculean task. So scientists use the repeating patterns of the DNA as a more convenient method. These can tell whether two DNA samples are from the same person, related people or non-related people. Using a small number of sequences that are known to vary greatly among individuals, scientists analyse them to get a probable match.

No two people in the world have the same DNA sequence. Except, of course, in instances of identical twins.

  • Because a person inherits his VNTRs (Variable Number of Tandem Repeats) from his parents, these patterns can be used to establish maternity and paternity. This is especially useful to determine paternity custody and child support litigation.
  • The traits of a human being are the result of information contained in the DNA code.
  • DNA isolated from blood, hair, skin cells or nails left at the scene of a crime, can be compared, through VNTR patterns, with the DNA of a suspect to determine guilt or innocence.

A conventional fingerprint that occurs only on the fingertips can be altered by surgery but a DNA fingerprint is the same for every cell, tissue and organ of a person.

Uses of DNA Fingerprints

  1. Detection of disorders: Alzheimer’s, thalassemia, cystic fibrosis are other disorders are detected in both prenatal and newborn babies using DNA fingerprinting. Parents are provided information on the risks of having an affected child so they can prepare themselves for proper treatment. Decisions can also be made in affected pregnancies using DNA fingerprint information.
  2. Research and Development: By studying inherited disorders that follow a pattern, DNA patterns associated with the disease may be studied. This may be a huge first step towards a genetic cure for the disorder.
  3. Crime scene identification: Blood, nails, semen, and hair found at the scene of a crime have all been invaluable biological proof for police and forensic labs to link suspects with criminal activities.

Further Reading

  1. http://www.genome.gov
  2. http://www.nigms.nih.gov