“The process in which many individuals of similar characters can be produced by asexual reproduction is called cloning”.
“The production of genetically identical copies of the organism or cells by asexual reproduction”.
Generally, no normal animal can reproduce naturally by cloning. Sometimes, some insects and many plants produce certain circumstances. But they do not produce clones regularly. Basically, it is a process of genetic duplication e.g. Twins, Cancer cells, Tumor cells.
“A clone is defined as a cell of an individual and all its asexually produced identical offspring. All members of a clone are genetically identical except when a mutation occurs”.
- An unfertilized ovum or egg is isolated from the female body.
- The nucleus of the egg is removed.
- The nucleus of a mature cell of an individual is introduced into the egg.
- This egg is transferred into the body of the female.
- After development, a new individual with a similar shape, structure, and character is produced. This whole procedure is called cloning.
Scientists in Scotland cloned a sheep in 1997. Some other mammalian species like mice and cows have been cloned. Two procedures are adopted for it:
The nucleus from a fertilized egg is removed. Another nucleus from a fully developed cell is taken. This nucleus is inserted into the above-fertilized egg. This altered zygote is implanted in a suitable womb. it completes its development there. The new individual formed is a genetically identical clone of the individual whose nucleus was used. In this way, it can make multiple copies of the desired genotype.
2. Embryo cloning
The dividing zygote or early embryo is taken. It is divided into more separate embryos. Each embryo develops a new identical clone. Identical twins are also produced by the same process. The cloned offspring of this type are genetically identical. But they carry the chromosomes of both parents. This type of cloning is used for producing identical cattle and other farm animals.
- Man can produce commercially valuable animals by cloning like horses, sheep, cows, etc.
- Some biologists are trying to clone human embryos. It can be used as a donor for the transplant of organs. There is much controversy about the cloning of humans.
- It is used for achieving eugenic aims (the aim of improving human genetic stock).
- New cells of body organs can be produced by this method. Such as skin, cells, liver cells
- Defected cells can be replaced by this process.
- Many hormones such as growth hormones can be prepared, by cloning.
- This technique can be used in plants to improve the quality of crops.
- It can develop criminal persons.
- The paternity of an individual cannot be defined, so it is a negative point in some societies.