They are employed in contemporary medicine because the sharp blades make wounds that heal more quickly. Human DNA from a single cell is around 6 feet long when uncoiled....
Also used by medieval craftsmen for cutting and polishing other materials including glass, metal, and stone.
Obsidian is volcanic glass formed when lava cools below its solidification point. The word "obsidion" comes from a Latin word meaning "a little Jupiter," probably alluding to the fact that like Jupiter, the planet of thunder and lightning, obsidian is often highly vesicular (spherical) when fractured.
In modern science, obsidian is studied for its chemical and physical properties as well as its ability to absorb energy in the form of heat during friction. The heat can be released by rubbing one's skin against it or, in the case of instruments, by rubbing their surfaces against each other. This property has been used to create tools out of obsidian that are still functional today. In science-fiction literature, it is often described as having a dark and dangerous surface quality.
Obsidian can be black, green, gray, brown, or pink depending on how long it takes for volcanic gases to dissolve into the molten rock before it flows into the ocean. It can also be white if the lava is very fresh.
Although it may not give pure DNA, total demineralisation is the optimum procedure for most situations of DNA extraction from bones. DNA extraction from aggregates eliminates inhibitors significantly more effectively and is also a useful procedure to use for determining the identity of excavated remains. However, DNA extraction from intact bone is best done by using a phenol-chloroform method.
Intact bone contains both organic and inorganic material that can inhibit DNA amplification. To ensure reliable results, it is important to remove all organics before beginning DNA analysis. This can be done by soaking the bone in a solution of sodium hypochlorite (household bleach) for several weeks or months until no color changes occur when exposed to light. Bleach will remove both fat and collagen, the main organic components of bone, resulting in a product that can be used with confidence for genetic analysis.
Once cleaned, the bone should be rinsed in water to remove any remaining bleach or other chemicals and then placed in a bag filled with an inert powder such as talc. This will preserve the sample by preventing contamination and also help minimize possible polymerase chain reaction (PCR) inhibition caused by residual metal ions. The bag can then be stored at -20 degrees C until ready for use.
DNA can be extracted from many types of preserved tissue including feathers, plants, fruits, vegetables, and meat.
Restriction enzymes (or restriction endonucleases) are employed in the laboratory to cleave DNA into smaller bits. The severing is always done at certain nucleotide sequences. Certain restriction enzymes recognize and cut various DNA sequences. Other restriction enzymes can be used to digest specific regions of DNA.
DNA is a complex molecule made up of two parallel chains of subunits called deoxyribonucleic acids or bases. The chain consists of alternating phosphate groups and sugar molecules: deoxyribose for humans. Each base is composed of a nitrogen-containing ring structure with a five-carbon ring attached to it. These bases are thymine, cytosine, adenine, and guanine. They form the language of life; each base pairs with another complementary base through hydrogen bonds between their nitrogenous rings. This pairing forms the basis of genetic information storage and transmission from generation to generation.
There are several ways that restriction enzymes have been used in the laboratory to break down DNA. The most common method is to mix some purified restriction enzyme with the DNA you want to study and let it work its magic on the DNA fragment. The restriction enzyme will find the specific sequence it belongs to and cut it apart, leaving blunt ends without any marks on them.