Prokaryotic organisms (organisms lacking a cell nucleus) such as bacteria create genetically identical duplicates of themselves using binary fission or budding.
Cloning is the process of generating a genetically identical copy of a cell or an organism. Cloning happens often in nature—for example, when a cell replicates itself asexually without any genetic alteration or recombination.
Prokaryotic organisms (organisms lacking a cell nucleus) such as bacteria create genetically identical duplicates of themselves using binary fission or budding.
In eukaryotic organisms (organisms possessing a cell nucleus) such as humans, all the cells that undergo mitosis, such as skin cells and cells lining the gastrointestinal tract, are clones; the only exceptions are gametes (eggs and sperm), which undergo meiosis and genetic recombination.
History:
Although the possibility of cloning humans had been the subject of speculation for much of the 20th century, scientists and policymakers began to take the prospect seriously in 1969.
J. B. S. Haldane was the first to introduce the idea of human cloning, for which he used the terms “clone” and “cloning,” which had been used in agriculture since the early 20th century.
In his speech on “Biological Possibilities for the Human Species of the Next Ten Thousand Years” at the Ciba Foundation Symposium on Man and his Future in 1963, he said: It is extremely hopeful that some human cell lines can be grown on a medium of precisely known chemical composition. Perhaps the first step will be the production of a clone from a single fertilized egg, as in Brave New World.
Assuming that cloning process is possible, I expect that most clones would be made from people aged at least fifty, except for athletes and dancers, who would be cloned younger. They would be made from people who were held to have excelled in a socially acceptable accomplishment…
What are the 5 major steps in cloning process?
- Choice of host organism and cloning vector.
- Preparation of vector DNA.
- Preparation of DNA to be cloned.
- Creation of recombinant DNA with DNA ligase.
- Introduction of recombinant DNA into the host organism.
- Selection of organisms containing vector sequences.
Principles of Gene Cloning:
A fragment of DNA, containing the desired gene to be cloned, is integrated into a suitable vector to generate a recombinant DNA molecule.
The vector acts as a vehicle that transports the gene into a host cell, generally a bacterium (host cell), although other types of living cells are also in use, in which this vector multiplies, producing multiple identical copies not only of itself but also of the gene that it carries.
The division in host cells, copies of the recombinant DNA molecule, which is then passed on to the progeny and further vector replication takes place. The clones of identical cells are produced after a large number of cell divisions. Each new cell in the colony contains one or more copies of the recombinant DNA molecule; the gene integrated in the recombinant molecule is now said to have been cloned.
Gene cloning:
The production of accurate copies of a specific gene sequence using genetic engineering techniques is called gene cloning. This technique is also known as recombinant DNA technology, gene cloning, and DNA cloning.
During the extraction of DNA from any organism, all of the genes are isolated, while in gene cloning, only a specific gene is copied to form clones. Gene cloning technology is an important method used for specific gene sequence isolation and amplification.
Gene cloning can be achieved by two different methods:
- Cell based DNA cloning
- Cell-free DNA cloning (PCR)
Requirements for Gene Cloning (Cell-Based):
- DNA fragment containing the desired genes to be cloned. Restriction enzymes and ligase enzymes.
- Vectors – to carry, maintain, and replicate cloned gene in a host cell.
- Host cell– in which recombinant DNA can replicate.
Gene cloning involves the following seven essential steps:
- Isolation of a specific DNA fragment containing a gene of interest that is to be cloned.
- Insertion of isolated DNA into a suitable vector to form recombinant DNA.
- Introduction of recombinant DNA into a suitable organism known as the host.
- Selection of transformed host cells and identification of the clone containing the gene of interest.
- Multiplication and expression of the introduced gene inside the host.
- Isolation of multiple gene copies/Protein expressed by the gene.
- Purification of the isolated gene copy or protein.
Application of gene cloning:
- The selected gene (GoI) can be isolated and its nucleotide sequence can be determined.
- Control sequences of DNA can be identified and analyzed.
- The function of proteins, enzymes, and RNA can be investigated and studied. Identification of mutants, e.g., gene defects related to specific diseases. Defected cells in organisms can be ‘engineered’ for specific purposes, e.g., insulin production, insect resistance, hormone production, TAP etc.
Advantages and disadvantages of cloning:
Advantages:
- Prevents extinction of certain species.
- Enables same-gender couples to have offspring.
- It greatly aids in the replacement of organs.
- Aid for diseases.
- Solves the problem of infertility.
- Increase in agricultural production.
Disadvantages:
- The process is not entirely safe and accurate.
- It is regarded as unethical, and the probability of abuse is very high.
- The offspring lack genetic uniqueness.
- It is not yet fully developed.
- 40 Different Types of Birds.
Examples of cloning that occur naturally are as follows:
- Vegetative reproduction in plants, e.g., water hyacinth, produces multiple copies of genetically identical plants through apomixis.
- binary fission in bacteria.
- parthenogenesis in certain animals.
Artificial cloning:
Human cloning is the process of creating a genetically identical copy (or clone) of a human. The term is generally used to refer to artificial human cloning, which is the reproduction of human cells and tissues. It does not refer to the natural conception and delivery of identical twins.
Example of artificial cloning:
Identical twins are the obvious examples, but perhaps more intriguing are armadillos, in which the offspring in a litter are all clones derived from one zygote (9). The simplest form of artificial cloning is embryonic cloning, which involves separating the blastomeres of an early embryo and forming two or more smaller embryos.