“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 clone regularly. Basically, it is a process of genetic duplication e.g. Twins, Cancer cells, Tumor cells.
“A clone is defined as a cell of individual and all its asexually produced identical offspring. All members of clone are genetically identical except when a mutation occurs”.
- Unfertilized ovum or egg is isolated from female body.
- Nucleus of egg is removed.
- Nucleus of a mature cell of an individual is introduced into the egg.
- This egg is transferred into the body of female.
- After development the new individual with similar shape, structure and characters is produced. This whole procedure is called cloning.
Scientists in Scotland cloned a sheep in 1997. Some other mammalian species like mice and cow 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 above fertilized egg. This altered zygote is implanted in a suitable womb.it complete 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 a desired genotype.
2. Embryo cloning
Dividing zygote or early embryo is taken. It is divided into more separate embryos. Each embryo is develops a new identical clone. Identical twins are also produced by same process. The cloned offspring of this type are genetically identical. But they carry chromosomes of the 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 horse, sheep, cow etc.
- Some biologists are trying to clone human embryo. It can be used as donor for the transplant of organs. There is much controversy about the cloning of human.
- It is used for achieving eugenic aims (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 negative point in some societies.