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The birth of Dolly means that human beings can use one tissue cell of an animal to produce the same life in large quantities, just like copying tapes or files, which is undoubtedly a breakthrough in the field of genetic engineering research.
, people cut plant branches and cut them into the soil, and soon they will sprout and grow new plants, which are plants with the same genetic material composition. This is called "cloning". Also, the tubers of plants such as potatoes are cut into many small pieces for reproduction, and the resulting offspring are also "clones". All these are asexual reproduction of plants, or "cloning", which is so common that almost everyone has seen it.
(Figure) Dolly, a cloned sheep, also has asexual reproduction in the animal kingdom, but it is more common in invertebrates, such as the division and reproduction of protozoa and the budding and reproduction of urochordates. But for advanced animals, under natural conditions, they can only reproduce sexually, so scientists must go through a series of complicated operation procedures to make them reproduce asexually. In the 195s, scientists successfully cloned an amphibian, Xenopus laevis, which opened a new chapter in cell biology.
In the late 198s, Britain and China successively used embryonic cells as donors to "clone" mammals. By the mid-199s, China had cloned five kinds of mammals, including mice, rabbits, goats, cows and pigs.
Dolly, a lamb whose genetic structure is exactly the same as that of the donor, was produced in 19 Long, which caused public outcry in the world. "Dolly" is special in that its life was born without the participation of * * *. The researchers first sucked the genetic material out of a sheep egg cell and turned it into an empty shell, then took out a breast cell from a 6-year-old ewe and injected the genetic material into the empty shell of the egg cell. In this way, an egg cell containing new genetic material but not refined is obtained. This modified egg cell divides and proliferates to form an embryo, and then it is implanted into the uterus of another ewe. With the successful delivery of the ewe, "Dolly" came to the world.
But why didn't other cloned animals have such a great influence in the world? This is because the genetic genes of other cloned animals come from embryos, and all of them are nuclear transplantation with embryonic cells, which cannot be strictly said to be "asexual reproduction". Another reason is that the embryonic cell itself is sexually propagated, and the genome in its nucleus is half from the father and half from the mother. Dolly's genome is all from a single parent, which is the real asexual reproduction. Therefore, in a strict sense, "Dolly" is the first truly cloned mammal in the world. On February 23rd, 1997, scientists from the Roslin Institute in Scotland, England, announced that their research team successfully used goat somatic cells "cloning technology" is the result of scientific development, and it has a very wide application prospect. In horticulture and animal husbandry, cloning technology is an ideal means to breed varieties with stable genetic properties, through which high-quality fruit trees and improved livestock can be cultivated. In the medical field, the United States, Switzerland and other countries have been able to use "cloning" technology to cultivate human skin for skin grafting. This new achievement has avoided the possible rejection of allograft and brought good news to patients. According to the report of China Xinhua News Agency on April 4, 1997, Cao Yilin, an expert in plastic surgery in Shanghai Ninth Personnel Hospital, successfully reproduced human ears in mice for the first time in the world, bringing hope for the repair and reconstruction of human missing organs. Cloning technology can also be used to multiply many valuable genes, such as insulin for treating diabetes, growth hormone that is expected to make dwarfism patients grow taller again, and interferon that can resist many diseases and infections.
Cloning is a major technological breakthrough in the field of biological science, which reflects the progress of nuclear differentiation technology, cell culture and control technology. Originally, it was a transliteration of English clone, which means a population of offspring individuals with the same genotype formed by asexual reproduction of organisms through cells, which is called "asexual reproduction" for short.
The word "cloning" was introduced into horticulture in 193, and then it was gradually applied to botany, zoology and medicine. In a broad sense, "cloning" is actually often encountered in our daily life, but it is not called "cloning".
in spring, the 6-year-old ewe has exactly the same genes, which can be described as a copy of its mother. It is worth noting that cloning technology will not only bring great benefits to human beings, but also bring disasters and problems to human beings. However, we can't stop its development because it may bring serious consequences. In the final analysis, its advantages outweigh its disadvantages, and it will be widely used in favor of human beings.