Cloning is a technique scientists use to make exact genetic copies of living things. Genes, cells, tissues, and even whole animals can all be cloned.
Types:
1. Therapeutic: In therapeutic cloning, the aim is to clone cells that make particular organs or types of tissue
2.Reproductive: In this we actually reproduce not organ but entire being(donor) from where we got genetic information
Methods:
1. Natural:This happens naturally when one embryo spontaneously divides into two or more embryos, thus creating identical twins or, sometimes, triplets or even more
2.Artifical:An existing embryo is mechanically divided into two or more embryos that are then allowed to develop naturally
3.Artifical and Donor: Through use of somatic cell of Donor.
Somatic cells are all the cells that make up an organism, but that are not sperm or egg cells. Sperm and egg cells contain only one set of chromosomes, and when they join during fertilization, the mother’s chromosomes merge with the father’s. Somatic cells, on the other hand, already contain two full sets of chromosomes. To make a clone, scientists transfer the DNA from an animal’s somatic cell into an egg cell that has had its nucleus and DNA removed. The egg develops into an embryo that contains the same genes as the cell donor. Then the embryo is implanted into an adult female’s uterus to grow.
Significance
- An embryo made by cloning can be turned into a stem cell factory. Stem cells are an early form of cells that can grow into many different types of cells and tissues. Scientists can turn them into nerve cells to fix a damaged spinal cord or insulin-making cells to treat diabetes.
- The cloning of animals has been used in a number of different applications. Animals have been cloned to have gene mutations that help scientists study diseases that develop in the animals.
- Livestock like cows and pigs have been cloned to produce more milk or meat.Example India is doing this project on Indigenous breeds
- Cloning might one day bring back extinct species like the woolly mammoth or giant panda.
- It overcomes the problem of immune rejection which is major concern during organ transplantation
- It can help in understanding process of ageing
Issues
- Many researchers think it is worthwhile to explore the use of embryonic stem cells as a path for treating human diseases. However, some experts are concerned about the striking similarities between stem cells and cancer cells. Both cell types have the ability to proliferate indefinitely and some studies show that after 60 cycles of cell division, stem cells can accumulate mutations that could lead to cancer. Therefore, the relationship between stem cells and cancer cells needs to be more clearly understood if stem cells are to be used to treat human disease.
- Researchers have observed some adverse health effects in sheep and other mammals that have been cloned. These include an increase in birth size and a variety of defects in vital organs, such as the liver, brain and heart.
- Another potential problem centers on the relative age of the cloned cell’s chromosomes. As cells go through their normal rounds of division, the tips of the chromosomes, called telomeres, shrink. Over time, the telomeres become so short that the cell can no longer divide and, consequently, the cell dies. This is part of the natural aging process that seems to happen in all cell types. As a consequence, clones created from a cell taken from an adult might have chromosomes that are already shorter than normal, which may condemn the clones’ cells to a shorter life span. Indeed, Dolly, who was cloned from the cell of a 6-year-old sheep, had chromosomes that were shorter than those of other sheep her age. Dolly died when she was six years old, about half the average sheep’s 12-year lifespan.
- Reproductive cloning would present the potential of creating a human that is genetically identical to another person who has previously existed or who still exists. This may conflict with long-standing religious and societal values about human dignity, possibly infringing upon principles of individual freedom, identity and autonomy. However, some argue that reproductive cloning could help sterile couples fulfill their dream of parenthood. Others see human cloning as a way to avoid passing on a deleterious gene that runs in the family without having to undergo embryo screening or embryo selection.
- Therapeutic cloning, while offering the potential for treating humans suffering from disease or injury, would require the destruction of human embryos in the test tube. Consequently, opponents argue that using this technique to collect embryonic stem cells is wrong, regardless of whether such cells are used to benefit sick or injured people.
India does not have specific laws regarding cloning but has guidelines prohibiting whole human cloning or reproductive cloning. India allows therapeutic cloning and the use of embryonic stem cells for research purposes
