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The history of DNA and use of DNA

By Leila Kozevnikov

Block:H

What is DNA?

History of DNA

DNA or deoxyribonucleic acid is a long molecule that contains our unique genetic code.

what is a genome?

a genome is made of a chemical called deoxyribonucleic acid, or DNA for short.

- DNA contains four basic building blocks or ‘bases?’: adenine? (A), cytosine? (C), guanine? (G) and thymine? (T).

-The order, of the sequence, is these bases form the instructions in the genome.

-DNA is a two-stranded molecule.

-DNA has a unique ‘double helix’ shape, like a twisted ladder.

the discovery of DNA

The discovery of DNA?

In 1952, an image was taken of a first X-ray picture of DNA. Which led to the discovery of its molecular structure by Watson and Crick. Also Rosalind Franklin created a technique called X-ray crystallography, it revealed the helical shape of the DNA molecule. Watson and Crick realized that DNA was made up of two chains of nucleotide pairs that encode the genetic information for all living things.

why is DNA so important?

Why is DNA so useful?

DNA is very important because it holds coding for proteins and genetic instruction guide for life and its processes. DNA holds the instructions for an organism's or each cell’s development, reproduction and death.

Different variations in your genetics can determine whether you’re likely to have food intolerance's, vitamin deficiencies, how you handle different parts of your diet, and which fitness and skincare remedies are likely to work for you.

Why is it used in criminal cases?

DNA in criminal cases

DNA can be used to identify criminals with incredible accuracy when biological evidence exists. DNA can be used to clear suspects and people mistakenly accused or convicted of crimes. In all, DNA technology is ensuring accuracy and fairness in the criminal justice system.

how is it tested?

How is DNA tested?

DNA (genetic) testing is performed by samples of blood, hair, skin, amniotic fluid or other tissue.

For example, a procedure called a buccal smear uses a small brush or cotton swab to collect a sample of cells from the inside surface of the cheek.

The sample or samples are sent to a laboratory where technicians look for specific changes in chromosomes, DNA, or proteins, depending on the suspected disorder.

The laboratory reports the test results in writing to a person's doctor or genetic counselor, or directly to the patient if requested.

how do they find it?

How is DNA collected from a crime scene?

Forensic scientists, crime scene investigators, and medical examiners, are the ones that properly collect DNA. A DNA sample can be collected from number of sources. Items found at a crime scene which was not involved in the actual crime, could be a source of DNA evidence.

At a crime scene, both biological evidence such as blood, and physical evidence like a weapon, could be a DNA sample that would help in a case. While evidence like blood or a weapon is easy to identify, DNA can also be completely invisible. For example if a person touched an object or weapon, skin cells or other forms of Touch DNA might have been left behind. For these reasons, a crime scene investigators have to thoroughly inspect and collect as much as possible from the crime scene.

Examples

For examples:

- In 1999, New York authorities linked a man through DNA evidence to at least 22 sexual assaults and robberies that had terrorized the city.

- In 2002, authorities in Philadelphia, Pennsylvania, and Fort Collins, Colorado, used DNA evidence to link and solve a series of crimes (rapes and a murder) perpetrated by the same individual.

- In the 2001 “Green River” killings, DNA evidence provided a major breakthrough in a series of crimes that had remained unsolved for years despite a large law enforcement task force and a $15 million investigation.

For example,

Assume that a man was convicted of sexual assault. At the time of his conviction, he was required to provide a sample of his DNA. It was entered into a DNA database. Several years later, another sexual assault was committed. A Sexual Assault Examiner worked with the victim and was able to have biological evidence from the rape. This evidence was analyzed, it was ran against a DNA database. A match was made to the man’s DNA profile. He was apprehended, tried, and sentenced for his second crime. In this fake case, he was prevented from committing other crimes during his period of incarceration.

Lynette White was murdered in 1988. When the three men first imprisoned for her murder were found to have been wrongfully convicted, it seemed that her killer would go unpunished.

However, with new technology invented they used to analyze DNA found at the scene of the murder. The only match was to a boy too young to have committed the murder, but DNA samples were taken from his family. The youth’s uncle confessed, and was sentenced to life imprisonment in 2003.

More examples

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