If it is human, how to clone it?

As we all know, the reproduction of living things is accomplished through reproduction. There are two ways of biological reproduction: one is called sexual reproduction and the other is called asexual reproduction.

Sexual reproduction is a reproductive mode in which bisexual germ cells (sperm and eggs) fuse and develop into offspring. Asexual reproduction does not combine hermaphroditic germ cells, but forms individuals through the division and reproduction of the organism itself or the growth and development of its somatic cells. Asexual reproduction is common in plants and some animals (such as single-celled animals and lower animals).

Cloning is a transliteration of the English word "clone", which comes from the Greek word klon, meaning seedling or twig, and refers to some plants that reproduce asexually or nutritionally. With the passage of time and the development of science, its meaning has increased a lot, such as a group of cells produced by a cell in vitro culture; DNA sequences produced by "parent" sequences, and so on. In a word, cloning refers to obtaining a group of cells or individuals with identical genes from a cell or individual through asexual reproduction.

The Monkey King in China's famous classic The Journey to the West can "transform" many the Monkey King as long as he pulls out a hair from his mouth and blows a fairy tale. Because pulling a finger on a finger will inevitably bring a group of cells, and this group of cells can cultivate a group of the same Sun Shengda. This is also asexual reproduction. It's just that Sun's skills are so high that he can "clone" thousands of himself in an instant. In short, cloning is asexual reproduction, that is, "replication" and "replication".

Second, plant cloning.

Asexual reproduction (cloning) is originally a low-level reproductive mode. The lower the level of biological evolution, the more likely it is to adopt this mode of reproduction, and the higher the level of evolution, the less likely it is to adopt this mode of reproduction. Because lower organisms, such as microorganisms, reproduce through self-division, and the genetic material of the offspring after division is exactly the same as their parents, in this sense, microorganisms have no "individuals" and they have not died. Although there are some differences between the parents and offspring of microorganisms in a strict sense, because their external nutritional environment will still be different, from the perspective of higher animals, this difference seems too insignificant. When this difference can be ignored, people can say that they are immortal to microorganisms. Death is the product of biological evolution to a higher stage. Normal cells or cancer cells cultured in vitro by cloning technology in biomedical research are also called "immortalized cell lines", that is, these cells are "immortal".

Biomedical research has entered the microscopic level. It is a very arduous task to cultivate immortal cell lines of normal or abnormal cells by cloning technology, but it has been paid more and more attention by scientific and medical circles in various countries. In agriculture, people have cultivated plants suitable for human needs by cutting and layering. In animal husbandry, countries are conducting research on cloning technology to produce more excellent animals. However, in higher organisms, the development from an adult somatic cell to an adult is a great development of cloning technology.

Many years ago, researchers at Cornell University in the United States stirred mature carrots at high speed to obtain single carrot cells, and then put these single cells into a growth medium to cultivate carrots with the same genes. This experiment confirmed the theory of plant cell totipotency. The so-called totipotency theory of plant cells means that every cell of plants, including somatic cells, has the potential to develop into a complete individual.

The theory of plant cell totipotency has been widely proved in the plant world. Now we can obtain a complete plant from any living cells, tissues and organs of plants by artificial culture in vitro, and produce many plants. This technique is called tissue culture. It has been used for industrialized production of test-tube seedlings of flowers and crops (such as sugarcane).

Third, the process of animal cloning.

The research of animal asexual reproduction has always been a subject explored by scientists. Because human beings have been cultivating livestock breeds through sexual reproduction for thousands of years, the result is that some excellent individuals or groups have been produced. They can meet people's needs and desires better than ordinary individuals. For example, a cow with a particularly high milk yield, a flock of sheep with a particularly high wool yield, an award-winning racehorse or an excellent police dog. However, the offspring who have sexual reproduction do not necessarily behave like their parents, and some even behave worse than their parents. The reason is that eggs or sperm only carry any half of the alleles that make up the parents, and the alleles can have almost unlimited combinations, so different offspring will be produced. There are great differences between brothers and sisters, because it is extremely difficult to have exactly the same genotype.

So it is difficult to maintain a phenotype through sexual reproduction. If an ideal phenotype is obtained, such as a cow with high milk yield, it is obviously valuable from an economic point of view to maintain, expand and reproduce this phenotype through asexual reproduction, that is, to produce many genetically identical individuals.

Egg cells are cultured into adults.

195 1 ~ 1959, Zhu Xian, a famous cell biologist in China, stimulated toad's egg cells with a glass needle with a diameter of 10 ~ 13um, and for the first time in the world, 25 adult toads, namely fatherless toads, were cultivated. They can live up to eight months.

Germ cells were used in the above experiments. Can animal bodies be obtained by culturing somatic cells? That is to say, plant cells are totipotent, and so are animal cells? There is no doubt that every animal cell, including somatic cells, has a complete set of genes of this species, but it has not been successful to culture somatic cells directly into animal adults. In order to prove that animal cells are totipotent, biologists have carried out a large number of nuclear transplantation experiments.

2. Nuclear transfer test

1939, scientists conducted the first nuclear transplantation experiment in amoeba. They transplanted the nucleus into the same kind of enucleated amoeba, and as a result, the recombinant amoeba could grow and reproduce.

Since 1963, Tong Dizhou, a famous biologist in China, has carried out a large number of nuclear transfer experiments in fish. 1980, they used carp blastocyst nucleus as donor nucleus and unfertilized mature eggs of crucian carp as recipient, and 2.7% of transplanted eggs developed into adult fish. The main characteristics of carp and crucian carp nuclear transfer fish are the same as those of carp, but the number of vertebrae is the same as that of crucian carp, and the number of lateral scales is between these two kinds of fish. The growth rate of this cell-engineered fish is 22% faster than that of carp, and it has been widely popularized in production.

1966, scientists conducted a nuclear transplantation experiment with the amphibian Xenopus laevis. They transferred the nuclei of tadpoles' intestinal cells into enucleated eggs, and as a result, 1.5% of the recombinant cells developed into adults. Their experiments proved for the first time that animal somatic cells are totipotent, but they have not been proved in mammalian somatic cells.

13. Cloning mammals with embryonic cells.

1986, British scientists used sheep 8-cell embryonic cells (cells before 8-cell embryos can show totipotency) as donor cells, and sheep egg cells as donor cells. As a result, the recombinant cells can develop into sheep adults, and then animals such as cattle, mice, rabbits and monkeys can be cloned from embryonic cells. It should be pointed out that this experiment is not to copy rams or ewes, but to copy their offspring, so there are still some shortcomings or defects in the experiment.

In China, mammals were cloned from embryonic cells, and in the late 1980s, they were cloned again. Sheep were cloned by Northwest Agricultural University and Jiangsu Agricultural College at 199 1. 1993, Institute of Development of China Academy of Sciences and Agricultural College of Yangzhou University cloned goats. 1995 south China normal university and Guangxi agricultural university cloned cattle. In addition, Hunan Medical College also cloned mice. However, cloning mammals from somatic cells other than embryonic cells was initiated by British scientist Wilmut.

Fourth, the birth of "Dolly"

"Dolly" is the first lamb in the world that was obtained by using somatic cells-mammary epithelial cells through nuclear transfer technology and complicated manual operation. The operation process is as follows:

1. Take out the egg from Scottish black-faced ewe (a kind of sheep) and suck the genetic material of the egg to make it into an egg with only cytoplasm.

Mammary epithelial cells were taken from ewes (B sheep) in the third trimester of pregnancy and cultured for 3-6 generations in vitro. These cells are treated with drugs to control their development and keep them at rest. This is a crucial step. Then resting cells are used as donor cells.

13. Introduce donor cells into the zona pellucida cavity of the egg. Then, donor cells and eggs are fused by electrical pulse stimulation to form reconstructed eggs.

The reconstructed egg was transplanted into the oviduct of a black-faced ewe (sheep C), and the oviduct of sheep C was ligated before, so that the embryo could not enter the uterus. C sheep play the role of cultivating embryos in vivo, which is called intermediate receptor.

Six days after the reconstructed eggs were transferred into the fallopian tube of C sheep, the embryos were washed out of the fallopian tube, and the embryos that developed normally to the morula stage and blastocyst stage were selected.

6. Transplant 1-3 morula or blastocyst into the uterus of Scottish black-faced sheep (Ding sheep). After the embryo was transplanted into the uterus, it continued to develop and finally gave birth to Dolly. This ewe is called "surrogate mother"

About 434 eggs were used in this project, and 277 reconstructed eggs were obtained. Six days after transplantation into the intermediate recipient, 247 embryos were rushed out, of which 29 (1 1.7%) developed into morula and blastocyst. Twenty-nine embryos were transferred to 13 surrogate mothers, and finally 1 Dolly was born, with a lambing rate of only 3.4%. If calculated by the number of reconstructed eggs, the lambing rate is less than 4 ‰. It can be seen that this technology needs to be improved. In addition, it should be noted that sheep cloning technology has not been completely replicated, and the cytoplasm of enucleated eggs will also contain a small amount of genetic material, which can also play an important or even decisive role in embryo development. The inheritance of organisms is the result of the interaction between nucleus and cytoplasm. Cytoplasmic genes are also DNA fragments, and their carriers are mainly some organelles, such as plastids and mitochondria. Cytoplasmic genes are independent to a certain extent and are generally not interfered by nuclear genes. Compared with nuclear genes, although the nucleus contains 99.9% genetic information, the expression of individual traits will still be influenced by the cytoplasm of eggs. So theoretically, "Dolly" sheep is not a complete replica. Because "Dolly" is only a lonely one, some people think that the statement that "Dolly" is a cloned animal is not accurate. Although only 1 "Dolly" has been obtained so far, it is a great scientific achievement that attracts worldwide attention.

Significance and economic value of verb (verb abbreviation) cloning technology

The magnificent human history is largely driven by technology: metal manufacturing and improved agriculture have separated civilization from the Stone Age; /kloc-the industrial revolution in the 0/9th century led to the rise of big machines and big cities; In the 20th century, physics was crowned. Physicists split atoms, revealed the wonderful world of relativity and quantum theory, and developed and utilized small silicon wafers. They changed the world through atomic bombs, transistors, lasers and microchips. Now, many experts believe that human beings are ready to meet a new wave of scientific and technological development in the future. As Robert Curl, a chemist at Rice University and winner of the 1996 Nobel Prize, said, "Now is the century of physics and chemistry, but the next century will obviously be the century of biology." Many scientists believe that with the birth of Dolly, a cloned sheep, the century of biology has arrived ahead of schedule.

The breakthrough of cloning technology shocked the world. People worry about human self-replication, but they often ignore the application and significance of other aspects. In fact, it has great theoretical value and broad application prospects in the research and production of basic life science, medicine and family science, and has great potential economic benefits. In the next 5 ~ 20 years, it will gradually form and cause a new world biotechnology industry revolution.

1. In the basic life science, the study of gene function has been carried out in a few animals, such as mice, and now it can be realized in many animals, which is helpful to reveal the gene function and life essence more clearly; It provides one of the most effective means to study the totipotency of mammalian cell development and the relationship between nucleus and cytoplasm. You can also clone various endangered animals, such as giant pandas, golden monkeys and even baiji.

In medicine, it can provide experimental animals with exactly the same nuclear genotype for medical research, which is beneficial for medical scientists to study diseases that have not yet found effective treatments and reveal the pathogenesis; The study of dedifferentiation mechanism is helpful to the study of anti-aging and its mechanism.

3. In agricultural science, excellent animals with strong disease resistance and high production performance can be quickly cultivated and propagated; We can study the pathogenesis of animals and seek new and effective therapeutic drugs.

How can intransitive verbs meet the challenge of "cloning age"

The success of cloning technology indicates that the last technical obstacle of "copying" mammals has been broken. In this way, it is theoretically possible to copy humans. Therefore, cloning technology not only brings us benefits, but also brings severe challenges to mankind. Once this technology is applied to human beings, it will bring extremely serious consequences to human society.

The return of human beings from sexual reproduction to asexual reproduction is undoubtedly a huge retrogression.

6. Without parents and affection, the "clone" society would become heartless.

3. "Clone" may reproduce through sexual reproduction in adulthood, and a large number of close relatives may get married unconsciously, with disastrous consequences.

From the sociological point of view, the continuous development and progress of mankind depends on everyone's continuous efforts and struggles. In addition to personal ideals, this power comes from people's obligations to society and family. If there is no obligation to support the elderly and raise the next generation, this power will be greatly reduced, which is also unfavorable to the development of the whole society.

A "replica" of a scientist may not become a scientist. Besides congenital reasons, acquired factors also play an important role in people's success. If these "replicas" are the burden of scientists, wouldn't society go backwards if they didn't study hard? Furthermore, what will society do if someone clones a large number of mentally retarded people in order to retaliate against society? If someone frantically "copies" a madman like Hitler and "cultivates" the day after tomorrow, it will make people feel even more horrible. ...

From the birth of cloned sheep, we are reminded of the energy relationship proposed by Einstein, a great scientist in 1905, which shows that there is huge energy in the nucleus. It never occurred to him that this theory became an important theory for making atomic bombs. If cloning technology is applied to human beings, it will be a great retrogression in the biological world. So we think that scientists are innocent in scientific research, and the problem is how to apply them.

We should "foster strengths and avoid weaknesses" and actively use the beneficial side of cloning technology to benefit mankind. At the same time, governments should strengthen legislation, strengthen supervision and prohibit the application of cloning technology to human beings in order to avoid the occurrence of human tragedies.

In short, the emergence and maturity of a new technology will inevitably bring new challenges and problems. With the improvement of moral law, people will eventually make good use of it.

A brief history of cloning technology (small data)

1938, the first modern embryologist, Hans of Germany? Dr Spider-Man suggested that mature nuclei should be implanted into eggs for mammalian cloning.

1952, using Spearman's idea, the first cloned frog appeared in the world.

1962, John? Gordon announced that he had cloned a tadpole from a mature cell, which triggered the first debate about cloning.

1984，Steen？ Willaderson cloned a sheep from embryonic cells. This is the first confirmed cloned mammal.

1995 10, Dr. Vikanti, an anesthesiologist in Massachusetts, USA, used improved tissue engineering to grow human ears on the back of mice, so that humans can cultivate skin and cartilage that can be transplanted to humans in the laboratory.

1In July, 1996, the Roslin Institute in Scotland, England, successfully cloned sheep Dolly from sheep breast cells.

1997 10, British experts bred headless frog embryos, enabling related technologies to manufacture human organs for medical transplantation.

1In July 1999, Japanese scientists cloned many cows and put their meat on the market.

In April 2000, American Advanced Cell Engineering Company cloned six calves younger than their actual age.

In 2000, American scientists successfully cloned a monkey "Tetra" through asexual reproduction technology, which means that there is no technical obstacle to cloning human beings.

2001165438+1On October 25th, the biotechnology company in Massachusetts, USA successfully cloned human embryos, which took an important step in cloning technology. However, the company said that its purpose is not to clone humans, but to obtain stem cells that can be used to treat various diseases such as Parkinson's disease and juvenile diabetes.

What is cloning?

The word clone is transliterated from clone. Before transliteration, there was a translation name-asexual cloning, which refers to the cell group or organic group obtained by mitosis of a single cell or the same ancestor. We can obtain cell clones by cell culture. In microbial experiments, we can get colonies by pouring dishes, which are actually bacterial clones. It can be seen that cloning is originally a noun, which refers to a group of cells or a group of individuals. With the development of molecular biology, nuclear transplantation and genetic engineering have appeared. Reconstructed cells can be obtained by nuclear transfer operation, and the reconstructed cells can be propagated into clones; Genetic engineering operation can splice the selected gene into the replicon of plasmid, and with the replication of replicon, the clone of DNA molecule can also be obtained. So some people call this operation cloning, that is, the word cloning is changed from a noun to a verb, nuclear transplantation is called nuclear cloning, and the cloning of DNA molecules obtained through genetic engineering is called molecular cloning. Here, cloning is an operation to realize asexual reproduction, a microscopic operation or a molecular biological operation, rather than asexual reproduction (or asexual reproduction operation) in a general sense. This may be the reason why the word cloning can exist without being replaced by asexual reproduction.

Cloned sheep

Dolly sheep, also called cloned sheep, is actually produced by nuclear cloning technology. Some people say that only Dolly sheep is the real cloned sheep. Other reports, such as cloned pigs and cloned cattle, are not real clones because they are developed from embryonic cells, which are produced by sexual reproduction. This is a misunderstanding, which is caused by the inaccurate grasp of the sexual process in time. The sexual process ends when the fertilized egg, the zygote, is formed. Once the fertilized egg divides, it has nothing to do with the sexual process. If divided embryonic cells are produced by sexual reproduction, then somatic cells are also produced by sexual reproduction. But in fact, zygotes are produced by mitosis. In other words, sexual reproduction is actually achieved through a sexual process and many asexual processes, and finally a surviving offspring is produced. Taking a cell from an embryo and making it develop into an individual should obviously belong to asexual reproduction. Therefore, in this sense, Hans Driesch is the founder of cloning technology (cell cloning technology), and his experiment of separating two mitochondria cells and making them develop into two sea urchins is the earliest cloning experiment. Human identical twins are produced by natural cell cloning. However, if cloned pigs and cloned cattle are bred by nuclear transfer, whether the donor cells are from early embryonic cells or differentiated cells, they are real cloning techniques, and they are much better than Duri Shu Gao.

Approaching "Gene Drugs"

In order to achieve a certain goal, people integrate the cloned foreign target gene (usually human DNA) into the chromosome of animal fertilized eggs, so that it can be expressed in animals and passed on to future generations stably. This kind of animal containing foreign genes is called transgenic animal. Scientists engaged in this research say that transgenic animals are natural gene drug factories, which can not only greatly reduce costs, but also expand production and obtain more gene drugs.

Using transgenic animals to produce gene drugs is a brand-new production mode, which has unparalleled advantages compared with traditional pharmaceutical technology. In the United States, for example, the annual demand for coagulation factor VIII is about 120g. In the past, this 120g coagulation factor VIII needed to extract1200,000 liters of plasma, and 600 blood donors needed to provide plasma, each donating 200 ml. With transgenic cattle, the milk yield of a cow is 65,438+0,000 kg per year. If each kilogram of milk can produce 10 mg of coagulation factor VIII, only 1.2 cows are needed to meet the demand. Take albumin as an example. The annual demand in the United States is 654.38+ 10,000 grams, which used to be extracted from 2 million liters of plasma. Now, only 5,000 cows can produce 2 grams of protein per kilogram of milk. In addition, infectious diseases such as hepatitis and AIDS that may be caused by protein extracted from human blood can also be avoided. Biotechnology is the most active technology today. 197 1 year, Nobel Prize winner Paul? Berg successfully spliced two different genes together for the first time, which made biotechnology develop into a new stage of gene recombination and transplantation.

Since then, gene recombination technology has achieved fruitful results. 1978 synthesized artificial insulin, 1979 realized the expression of growth hormone gene in E.coli, 1982 successfully developed artificial interferon, and gene pharmacy embarked on the road of industrialization. However, at present, gene drugs are produced by cultivating Escherichia coli and animal cells through gene recombination technology. It is impossible for lower organisms such as Escherichia coli to produce drugs with complex structures, and the cost of animal cell culture is too high. Therefore, the use of gene recombination and transplantation technology to cultivate transgenic animals to produce drugs came into being, and British scientists pioneered the use of transgenic animals to extract drugs. 1At the end of 1997, the British company PPL Therapeutics took the lead in breeding 200 sheep carrying human genes by using the "nuclear transformation" method adopted when Dolly was cloned, and successfully extracted α- 1 antitrypsin from milk. This is the first time that scientists have extracted pharmaceutical ingredients that can be used to treat human diseases from sheep milk cultivated by genetic engineering, laying the foundation for establishing an "animal pharmaceutical factory". Subsequently, Finnish scientists implanted the human erythropoietin gene into the fertilized eggs of dairy cows to create a dairy cow that can produce erythropoietin. Theoretically, this kind of cow can extract 60-80 kilograms of erythropoietin a year, which is more than the consumption in the world at present.

If you are a football fan, you definitely want another Ronaldo to appear in the world. If you are a music lover, you certainly hope to have another Beethoven; Another Edison and Einstein is also the dream of many people. An ancient Greek philosopher once said, "There can't be two identical leaves in the world". In other words, all the above dreams can only be fantasies, and there is no possibility of realization. But now the situation has changed, and with the new biotechnology "cloning", it may be possible to do this. So what is cloning? What are the highlights? Today, let's approach together-"wonderful cloning".

What animals and plants around us are born with the ability to clone? Plants and animals with cloning ability are: potatoes, earthworms, mulberry trees, loofah vines, chlorophytum, jellyfish, sea cucumbers and cacti. After the jellyfish is injured, the wound will heal automatically. Octopus tentacles can regenerate. Lobster's big pliers are dropped and will grow back. There are begonia and rich bamboo, and they make a living by pruning. Gecko when it is in danger, it will break its tail and grow back.

Can you find out the similarities between these animals and plants that are born with cloning ability and tell what cloning is in your own words? Offspring not produced by the union of germ cells.

Cloning technology can benefit mankind: it can expand the reproduction of infertile animals such as mules and save endangered animals.

If you master cloning technology, what do you want to clone? Why did you clone it? Requirements: 1, the idea should be wonderful; 2. Ideas should be beneficial to human beings; 3, the expression should be organized, and the tone should be appropriate.

If I want to clone, I will clone countless pairs of Ming Che's eyes. Many people take a pair of good eyes for granted, but I don't think so. When you see those dull eyes and hear the call of a bright heart, won't your heart tremble? God is unfair to them, let science create light for them and let society let them experience true love. I firmly believe that "people-oriented technology" is not an empty talk. So I want to clone my eyes and let more people see the light again.

I want to clone dinosaurs. Because I like dinosaurs and want to reproduce the glory of the dinosaur era. And it has the conditions to clone dinosaurs, because the Antarctic in the dinosaur era may be in the temperate zone. When the dinosaur died, the body was hidden in the South Pole. At this time, the South Pole was probably already in the ice and snow. Because cold can prevent corpses from rotting, it is possible to extract dinosaur DNA, clone dinosaurs, and broaden the horizons of future generations.

I don't advocate cloning some prehistoric creatures like him, such as dinosaurs and fierce ants. Because the survival and extinction of any living thing is beyond human control, human beings should strictly abide by the "laws of nature" and let the development of living things go with the flow. If we go back to the past, we may destroy the ecological balance.

I want to clone water. At present, there is a serious shortage of fresh water resources in the world, which can no longer sustain human survival, and human beings are still wasting water indefinitely, so I want to clone water.

I want to clone food, save people who are suffering from pain and hunger in Africa, and let them live a well-fed life.

As we all know, tropical rain forests are the lungs of the earth. Amazon Plain is the largest tropical rain forest in the world, accounting for 50% of the total tropical rain forest area on the earth, reaching 6.5 million square kilometers. It is rich in natural resources and various species, and is called "a paradise for biologists". However, Amazon is not loved by people because of its wealth. Since the 1970s, people's deforestation has made one third of their faces disappear before our eyes, which will mean that the oxygen for human survival will be reduced by one fifth. So, I want to clone the Amazon rainforest and put it in the Sahara desert to purify the environment.

I object to what three students said just now. Their ideas are very good, expressing their concern and good wishes for the country and people. But water, rainforests and grains have no cells. How to clone them? (Laughter) (Someone interrupts in a low voice): Water can. There are water molecules.

If I have cloning technology, I will clone the Monkey King, because he is omnipotent and can realize many of our ideals of changing society. (Laughter).

Teacher: Thanks to these students for their bold and novel "cloning ideal". Whether it is inconsistent with scientific principles or not, it expresses everyone's good wishes. I hope that science and technology can make society progress and make human life happier! Around "Cloning technology benefits mankind?" ! "Discuss the debate. )

Teacher: Debate requirements: (1) clear and fluent language, loud voice; (2) The views are clear and the arguments are sufficient; (3) There should be both "reason" and "courtesy" when refuting the other party's point of view.

(Take "cloning technology can benefit mankind" as affirmation, "cloning technology can not benefit mankind" as negation.