When the liver is damaged enzymes only found normally in the liver break into the blood stream, and testing for these is used to confirm liver damage. Enzymes are actually used as medicines, usually to replace enzyme deficiencies in patients, like when blood-clotting factors are used to treat haemophilia, or the opposite where proteases are used to degrade fibrin; use of proteases can prevent the formation of dangerous blood clots. .
PCR (polymerase chain reaction) is a "test tube" production line for churning out large numbers of identical copies of a molecule of double stranded DNA. Each strand is copied, and then copied, and so on until enough DNA has been made for analysis. PCR is sensitive enough to copy as little as one molecule of DNA; therefore it can be used to detect the presence of bacteria and viruses (via their genes) before they are present in sufficient numbers to produce symptoms. This is useful for testing HIV and forensic science; they only need one cell from the suspect. It can be used to copy DNA from bloodstains and semen samples in cases of assault and rape. It can be used to copy DNA from a single hair found at the scene of a crime so that a genetic fingerprint can be made that may lead to the identification of the criminal. It has even been used to copy DNA from Egyptian mummies, the remains of extinct animals and even a termite embalmed in amber. .
Enzymes and food have been natural partners since ancient times. Traditional roles of enzymes in the food industry have been in the processing of bakery goods, alcoholic beverages and starch conversion, but interest now lies on newer and varied applications such as hydrolysis of lactose, preparation of modified fats/oils and processing of fruit juice. Enzymes also have a wide range of industrial uses including starch conversion, manufacturing textiles, leather, paper, detergents, and medical uses, which are mentioned above.