About
DNA
Deoxyribonucleic acid (DNA) is often referred to as the
molecule of heredity as it is responsible for the genetic
propagation of most inherited traits. These traits can range
from hair color to disease susceptibility.
During
cell division, DNA is replicated and can be transmitted to
offspring during reproduction. Lineage studies can be done
based on the facts that the DNA in mitochondria (mitochondrial
DNA) only comes from the mother, and the male "Y" chromosome
only comes from the father.
Every
person's DNA, their genome, is inherited from both parents. The
mother's mitochondrial DNA together with twenty-three
chromosomes from each parent combine to form the genome of a
zygote (fertilized egg).
As a
result, with certain exceptions such as red blood cells, most
human cells contain 23 pairs of chromosomes, together with
mitochondrial DNA inherited from the mother.
DNA In Crime
Forensic
scientists can use DNA located in blood, semen, skin, saliva,
or hair left at the scene of a crime to identify a possible
suspect, a process called genetic fingerprinting or DNA
profiling.
In DNA
profiling the relative lengths of sections of repetitive DNA,
such as short tandem repeats and minisatellites, are
compared.
DNA
profiling was developed in 1984 by English geneticist Alec
Jeffreys, and was first used to convict Colin Pitchfork in 1986
in the Enderby murders case in Leicestershire,
England.
Many
jurisdictions require convicts of certain types of crimes to
provide a sample of DNA for inclusion in a computerized
database.
This has
helped investigators solve old cases where the perpetrator was
unknown and only a DNA sample was obtained from the scene
(particularly in rape cases between
strangers).
This
method is one of the most reliable techniques for identifying a
criminal, but is not always perfect, for example if no DNA can
be retrieved, or if the scene is contaminated with the DNA of
several possible suspects.
Health
Related Websites
The National Cancer
Institute
The National Eye
Institute
The National Heart, Lung,
and Blood Institute
National Institute on
Aging
National Institute of
Allergy and Infectious Diseases
National Institute of
Arthritis and Musculoskeletal and Skin Diseases
National Institute of
Diabetes and Digestive and Kidney Diseases
National Institute on Drug
Abuse
National Institute of Mental
Health
National Institute of
Neurological Disorders and Stroke
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