"Genetic engineering" can be divided into broad and narrow senses. "Genetic engineering" in the broad sense includes genetic operations at the cellular level (cell engineering) and genetic operations at the molecular level (genetic engineering); "genetic engineering" in the narrow sense is genetic engineering - see recombinant DNA technology (recombinant DNA technology).
A genetic technology that uses biochemical means to remove the genetic material from the cells of one organism, cut and recombine it outside the body, and then introduce it into the living cells of another organism. To change the genetic traits of another organism or create a new biological species, also called genetic engineering.
As the saying goes: "A crop depends entirely on fertilizer." Among fertilizers, nitrogen fertilizer is the most important.
All kinds of crops require a large amount of nitrogen fertilizer during their growth. However, leguminous crops such as soybeans and peanuts can grow well if they use less or even no nitrogen fertilizer. Why is this? It turns out that each leguminous crop has its own many "small fertilizer plants." These "little fertilizer plants" are large numbers of rhizobia bacteria growing in their roots. Rhizobium bacteria have a special ability - nitrogen fixation. They can collect nitrogen in the air and produce ammonia, which is continuously supplied to leguminous crops.
Except for leguminous crops, other crops such as wheat, rice, corn, sorghum, etc. do not have such "small fertilizer plants". To obtain high yields, a large amount of nitrogen fertilizer must be applied.
Is there a way for these grass crops to produce their own nitrogen fertilizer and be self-sufficient? Only after the emergence of the new science of "genetic engineering" did this fantasy become possible.
What is genetic engineering
"Heredity" refers to biological matters; "engineering" refers to architectural matters.
How are "genetics" and "engineering" connected together? Can people design new creatures just like they design new buildings?
Yes, that's exactly it. This is what the new science of genetic engineering is about.
Everyone knows that all kinds of organisms are basically the same as their previous generations, and they can also give birth to next generations that are basically the same as them. This phenomenon is called heredity. However, the next generation cannot be exactly the same as the previous generation. There will always be some very subtle differences. This phenomenon is called mutation. So, what determines heredity and variation? After scientific analysis, it has now been concluded that this substance is nucleic acid. Nucleic acids are mainly concentrated in the nucleus of each cell. The next generation of organisms receives the nucleic acids of the previous generation, which play a decisive role in their growth and development. Therefore, as long as we deeply study the chemical structure of nucleic acids, we can uncover the mysteries of inheritance and mutation.
Nucleic acid is a very complex compound. There are two types: one is deoxyribonucleic acid, usually represented by DNA; the other is ribonucleic acid, usually represented by RNA.
Let’s take deoxyribonucleic acid as an example. It is a long-chain polymer, and a molecule is composed of dozens to billions of nucleotides. Nucleotides can be divided into four types. The different arrangements of these four types of nucleotides determine the heritability of various organisms. Nucleotides are like telegraph characters. Although there are not many telegraph characters, the order of arrangement can be ever-changing. Each group of different character arrangements represents a Chinese meaning. In the same way, although there are only four types of nucleotides, thousands of nucleotides are arranged in different sequences and become different genetic genes. Because the sequence of nucleotides resembles a telegraph code, it is called the "genetic code." Organisms rely on various "genetic codes" on long chains of DNA molecules to ensure that genetic traits are passed on from generation to generation. If there is any error or omission in the "genetic code", it will inevitably affect the growth and development of the next generation and cause mutations.
Since genetic genes are on long chains of DNA molecules, if people identify these codes, can they purposefully modify organisms by adding or removing some genes?
Genetic engineering was born based on this idea. It uses a method similar to engineering design. It first designs organisms, isolates the DNA molecules in one organism, artificially "cuts" them, recombines them, and then installs them into the cells of another organism, making these molecules Organisms with new structures and functions.
Operating on bacteria
It is certainly not an easy task to turn this idea into reality. Scientists from many countries are now studying this technology and have already figured out some ways.
For example, if we want a certain type of bacteria to synthesize silk proteins and produce silk like silkworms, we can separate and "cut" the DNA molecules of silkworms. The "gene" that makes silk protein. Then a DNA molecule called a "plasmid" is extracted from the bacterial cell, connected to the "cut" gene, and then returned to the bacterial cell.
This method is simple to say, but to achieve this, at least two enzymes are required. Because the molecules of DNA are so small that they can only be seen with an electron microscope. To "cut" the "gene" that makes silk protein from the chain, of course you can't use ordinary scissors, but use a " Restriction endonuclease". This is a protein that has a special ability to recognize specific sites on DNA molecules and divide it into fragments of different lengths. Sometimes it's just right and the entire gene is cut out, and sometimes the gene is cut out. That doesn't matter, because so far, hundreds of restriction endonucleases have been discovered, which means there are hundreds of various scissors, and you can always choose a suitable one that will not cut the gene. "Scissors". A DNA molecule called a "plasmid" in a bacterial cell must also be cut with the same "scissors" so that the two "cuts" exactly match each other. In order to connect them more firmly, another enzyme, called ligase, is used to erase the seams.
After such a set of operations, the bacteria will synthesize silk protein like silkworms and have the ability to produce silk.
Up to now, this method is still in the experimental stage and has no practical application. But we believe that if we continue along this path, one day in the future we will be able to transplant genetic genes from animals and plants into bacteria, or move genetic genes from bacteria into animal and plant cells. In this way, it is possible for people to create many new species of organisms. By that time, the new technology of genetic engineering will be widely used in agriculture, industry, medicine and national defense, bringing about amazing changes in these fields.
Artificial creation of new biological varieties
Everyone knows that cultivating excellent varieties is an important way to improve grain yield and quality. The most effective breeding method currently is sexual crossbreeding. However, this method can only be carried out between organisms of the same species or closely related organisms. Distantly related organisms, such as grass crops wheat and leguminous crops soybeans, cannot hybridize because their germ cells Cannot be combined.
"Genetic engineering" is not subject to this restriction. At present, scientists want to take out the nitrogen-fixing genes from rhizobia of leguminous crops and transplant them into bacteria living next to the roots of crops such as wheat, rice, and corn, so that these bacteria can also have the ability to fix nitrogen. This ability can be passed down from generation to generation, continuously supplying plants with nitrogen fertilizer.
Scientists are also planning to take another approach, directly transplanting the nitrogen-fixing genes of rhizobia into the cells of crops such as wheat, rice, and corn without the help of bacteria, so that they can fix nitrogen by themselves. If this method is successful, it will be equivalent to setting up a "small fertilizer factory" for each crop. Now every production team in rural areas of our country has to buy chemical fertilizers every year, and this huge amount of money can be saved in the future.
Let bacteria give us medicine
Genetic engineering will also have a great impact on industrial production. Let us also give an example:
Insulin, a specific drug for treating diabetes, is currently extracted from the pancreas of pigs, cows and other livestock. One ton of pancreas can only produce a little more than half a tael of insulin, which is far less than the needs of diabetic patients. If we transplant the insulin-producing gene in pancreatic cells into E. coli, we can make E. coli produce insulin. E. coli reproduces much faster than higher organisms. Under suitable conditions, it only takes 25 minutes to reproduce for one generation, and no more than two hours at most. Once this trial is successful, insulin production could be greatly increased and costs significantly reduced.
Treat genetic diseases
Genetic engineering can also help people treat genetic diseases.
Some people become born idiots because they lack a "galactase" in the cells of their bodies.
In order to treat this disease, doctors can extract the "gene" of bacteria that produce galactase and transplant it into the cells of the patient's body, so that the patient can produce galactase himself. This may cure the idiot. This treatment using genetic engineering is called gene therapy.
According to statistics, there are as many as one to two thousand genetic diseases in humans, most of which are currently incurable. With the development of genetic engineering, it may become a treatable disease in the future. What a joy this is!
Genetic engineering is an emerging science that has developed rapidly in recent years and is being studied in many countries. However, some people abroad are opposed to genetic engineering. They are afraid of the emergence of viruses or bacteria that can easily cause cancer, making cancer widespread; they are afraid of the emergence of new strains of bacteria that are resistant to antibiotics, making it difficult to treat diseases; they are also afraid of disrupting and destroying the functions of normal cells, causing strange diseases... In the United States, the issue has sparked heated scientific debate and a number of safety measures have been mandated.
The various concerns about genetic engineering are all inferred based on existing knowledge. Whether it is really that dangerous needs to be determined through experiments. When we carry out this research work, of course we must take it seriously and take necessary safety measures, but there is no need to be afraid.
Whether a new science brings disaster or blessing to mankind does not actually depend on the science itself. Just like atomic energy, it can be used to benefit mankind or to kill people. arms. When we study genetic engineering, we should strive to develop aspects that are beneficial to the people and limit and eliminate aspects that are harmful to the people. We must also be wary of and oppose the use of genetic engineering for biological warfare. We believe that genetic engineering will definitely become a powerful tool for humans to transform and conquer nature.