The Artificially Improved Varieties—Genetic Engineering

Genetic engineering：

the private customization

of the universe

Its difficult to explain the principle of genetic engineering， but you can understand it by a game called “2048” recently popular on the internet. The game is very simple， you need to move the numbers 2 and 4 constantly generated in a square of 4*4， and combine them to generate a bigger number， until the number 2048 turns up. This game makes many people fondle admiringly， they cannot stop once start.

The principle of genetic engineering is similar to that of rearranging the source code in the game 2048， both customize their special functions needed. The genetic codes within the biology genes trace out the forms and habits of every kind of living things——such as the ability to compound some chemical substance. If we can change the living things gene as we change the game code， then we will be able to transform the living things to what we want by DIY. Of course， people who can handle the game 2048 easily may be not able to change the big game “ the Legend of Sword and Fairy V” （ if the source code could be known in public）， in the same way， before completely understanding all the mysteries of the biological genes， people have to gropingly do some gene modification jobs to the living things， those microorganisms with relatively simple genetic codes are easier to be modified.

Combine the gene with

scissors and glue

Except for some virus， the genetic information of most living things are always reserved in DNA. If you want to modify the gene， you should firstly learn how to change the DNA， which is just like you should learn how to bring up the source codes with editor if you want to change the game. The DNA is like a long paper tape written on genetic codes. You have to scissor the paper at a designated spot if you want to change the genetic codes， then you can insert a length of new paper tape， or replace a length of old paper tape with new， and stick them up again. In 1970， the American biologist Hamilton O. Smith and his student Kent W. Wilcox found the first kind of enzyme that can cut off the DNA at a designated spot， that is DNA restriction enzyme. Since then， scientists have found hundreds kinds of DNA restriction enzymes， which can recognize dozens of different DNA sequences， and are called “magical scissors” to cut off DNA. In 1967， three laboratories found the DNA ligase at the same time. With the DNA ligase， the cut off DNA could be stuck up again， so we call the DNA liagse “magical glue”.

The bio-pharmaceuticals

firstly play the role

The earliest two kinds of medicine produced by genetic engineering are recombinant human insulin and recombinant human growth hormone. Insulin is hormone secreted by pancreas islet， used to promoting the cells to resolve the glucose. Diabetes is a chronic disease does great harm to human body. For patients with type 1 diabetes， injecting insulin is apparently the most effective therapy.

You can get only 1 gram of insulin from dozens of kilograms of animal pancreas， so its very expensive. Moreover， the pesticide effect of animal insulin is far less than human insulin. Compared with insulin， another medicine called growth hormone is much more expensive. This insulin is secreted from the hypophysis cerebri of human， whose main function is to promoting the growth of children. So the growth hormone can be used to cure the genetic disease called “Paltaufs dwarfism”. However， the growth hormone can be got only from the human body. To get 1 gram of growth hormone， you need the hypophysis cerebris from ten bodies.

The bio-pharmaceuticals firstly play the role

Genetic engineering is not only used in transforming microorganisms， but also the higher animals and plants， that is so-called “genetically modified animals and plants”. Although the research and development of genetically modified plants is already mature， and has been used in agricultural production for more than 20 years， the genetically modified plants such as genetically modified salmon has also passed the safety test， and is coming into the market， many people still doubt the safety of these genetically modified higher living things. So the social acceptability of these genetically modified animals and plants will be influenced.

By contrast， the earlier commercialization of genetically modified microbe engineering has done more jobs， such as compounding biogasoline to remit the energy crisis. The transformed microorganisms can also be used to degrade oil contamination， dioxin， plastic and other refractory pollutants in the common nature.