Activity 131 DNA DetectivesIntroduction Bones Can
Activity 1.3.1: DNA Detectives
Introduction
Bones can provide a snapshot of the identity of a person- they can predict height, stature, gender, ethnicity and even age. However, it is what lies inside these hard calcified tissues, the DNA housed inside the body’s cells, that holds the key to true genetic identity. Tissue is made up of many cells, the building blocks of life. Tucked inside the body’s cells, you will find chromosomes. These structures house your genes and contain the DNA code necessary for the production of all of the proteins that keep your body functioning. Your DNA provides a unique code of over three billion base pairs. Unless you are an identical twin, there is no other person on the planet with your same code. And although only one tenth of one percent of this DNA differs from person to person (that’s still 3 million base pairs!), the regions that vary provide a true genetic blueprint of an individual. This amazing molecule is tiny -- invisible to the naked eye -- but it is often the only key that can link killers to a crime, parents to their children or a person to his/her own bones.
In PBS, you learned about the molecular biology techniques that allow scientists to explore our DNA. PCR, Polymerase Chain Reaction, is the copy machine; the revolutionary process that allows scientists to replicate even the tiniest speck of DNA. Restriction endonucleases (enzymes) are the molecular scissors that can cut DNA in specific locations. Your specific code determines the number of times this set of scissors will snip and the number and size of DNA pieces that will be left behind. These pieces can then be separated and compared using the process of gel electrophoresis. As these fragments move, their varying lengths propel them through the gel at different speeds. Scientists can use these RFLPs, Restriction Fragment Length Polymorphisms, a set of DNA puzzle pieces unique to only you, to create a pattern called a DNA fingerprint. Similar to the unique
Introduction
Bones can provide a snapshot of the identity of a person- they can predict height, stature, gender, ethnicity and even age. However, it is what lies inside these hard calcified tissues, the DNA housed inside the body’s cells, that holds the key to true genetic identity. Tissue is made up of many cells, the building blocks of life. Tucked inside the body’s cells, you will find chromosomes. These structures house your genes and contain the DNA code necessary for the production of all of the proteins that keep your body functioning. Your DNA provides a unique code of over three billion base pairs. Unless you are an identical twin, there is no other person on the planet with your same code. And although only one tenth of one percent of this DNA differs from person to person (that’s still 3 million base pairs!), the regions that vary provide a true genetic blueprint of an individual. This amazing molecule is tiny -- invisible to the naked eye -- but it is often the only key that can link killers to a crime, parents to their children or a person to his/her own bones.
In PBS, you learned about the molecular biology techniques that allow scientists to explore our DNA. PCR, Polymerase Chain Reaction, is the copy machine; the revolutionary process that allows scientists to replicate even the tiniest speck of DNA. Restriction endonucleases (enzymes) are the molecular scissors that can cut DNA in specific locations. Your specific code determines the number of times this set of scissors will snip and the number and size of DNA pieces that will be left behind. These pieces can then be separated and compared using the process of gel electrophoresis. As these fragments move, their varying lengths propel them through the gel at different speeds. Scientists can use these RFLPs, Restriction Fragment Length Polymorphisms, a set of DNA puzzle pieces unique to only you, to create a pattern called a DNA fingerprint. Similar to the unique