DNA Analysis

DNA is the abbreviation for deoxyribonucleic acid. DNA is one of the basic "building blocks" of life and is present in all living organisms. DNA is an even more unique identifier than fingerprints and is contain inside every living cell in the body.

A person's DNA is the same in every cell that has a nucleus. Almost all cells have a nucleus, red blood cells do not. So red blood cells do not have DNA. Blood, however can still be tested for DNA because there are other components in it which do have nucleated cells. The DNA in a person's blood is the same as the DNA in their skin cells, semen, and saliva.

DNA is comprised of four building blocks called bases. The building blocks are:

These are commonly referred to as C, G, T, A.

The bases line up along the DNA backbone which is a long chain of sugar and phosphate molecules. The order that the bases line up is important because that is what makes every individual unique.

Each molecule of DNA actually has two strands of sugar phosphate molecules and they twine together to form a helix structure due to the attractive forces of the bases. Each base on one strand will pair with another base on the opposite strand to form the "ladder" in between the backbones.

There are rules in molecular biology and biochemistry, and these rules state that the bases can only pair with their "partners". It just so happens that C and G are partners and A and T are partners. So if you have an A on one strand, the opposite strand MUST have a T paired with it.

When solving crimes, a forensic DNA laboratory will use the evidence samples collected from the crime scene and run tests on them to extract out the DNA and analyze it. The DNA is first amplified (copied over and over again so that a little itty bitty amount turns into lots of DNA) and a tests are run to make the DNA pattern that can be used to compare against a suspect.

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