SHADOW OF DNA Part 5

DNA STRUCTURE AND ITS ROLE IN FORENSIC SCIENCE.......


DNA stands for deoxyribonucleic acid and is the
material in most organisms, including humans,
that controls hereditary properties. It is the
building block that is fundamental for the entire
genetic makeup of an individual or being.
Although a small amount of DNA can be found in
the mitochondria, most DNA is found in the cell
nucleus. The same DNA is present in nearly all of
the cells of a person’s body which means that the
DNA in blood cells is the same as the DNA in
saliva and skins cells. Although the DNA is
virtually the same in almost every aspect of a
person, it differs between another person unless
they are identical twins. The long-term
information that is stored in DNA is used to
instruct the functioning and development of living
organisms except for some viruses.
DNA Structure
Each DNA is made of two nucleotides that have
backbones made from phosphate and sugar
groups and are joined together by ester bonds.
The nucleotides are anti-parallel, which means
they run in the opposite direction of each other.
Four types of molecules, called bases, are
attached to each sugar. These bases are:
adenine
thymine
cytosine
guanine
The bases are sequenced along the backbones in
a way that encodes information. Guanine and
adenine are purines, which are the larger of the
two types of bases. The other type of bases is
pyrimidine which consists of cytosine and
thymine.
The information that is encoded is used by use of
the genetic code; this shows the specific
sequence of amino acids within the proteins. The
process of reading this information is called
transcription. DNA is organized within cells as
long structures called chromosomes; when these
chromosomes are duplicated before they are
divided, the process is called DNA replication.