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Do clones ever occur naturally? -

Clones do occur naturally. Some plants and single-celled organisms, such as bacteria, produce genetically identical offspring through a process called asexual reproduction. In asexual reproduction, a new individual is generated from a copy of a single cell from the parent organism.

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What are the types of artificial cloning? -

There are three different modern types of artificial cloning. They are gene cloning, reproductive cloning, and therapeutic cloning.

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Gene cloning -

Gene cloning produces copies of genes or segments of DNA. It's also known as DNA cloning, and it's a very different process from reproductive and therapeutic cloning.

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Reproductive cloning -

Reproductive cloning produces copies of whole animals and organisms. It transplants nuclei from body cells into eggs that have had their nucleus removed. That egg is then stimulated to divide using an electrical charge and is implanted into the uterus of a female.

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Therapeutic cloning -

Therapeutic cloning produces embryonic stem cells for experiments aimed at creating tissues to replace injured or diseased tissues. These cells are stimulated to divide and are grown in a Petri dish rather than in the uterus.

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How are genes cloned? -

The procedure consists of inserting a gene from one organism, often referred to as foreign DNA, into the genetic material of a carrier called a vector.

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How are genes cloned? -

Examples of vectors include bacteria, yeast cells, viruses, or plasmids. After the gene is inserted, the vector is placed in a laboratory where it will multiply.

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How are animals cloned? -

Animals are cloned in one of two ways. The first is called embryo twinning. Scientists first split an embryo in half. Those two halves are then placed in a mother’s uterus, where each embryo develops into a unique animal. The two animals share the same genes.

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How are animals cloned? -

The second method is called somatic cell nuclear transfer. 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.

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What animals have been cloned? -

Over the past 50 years or so, scientists have conducted cloning experiments in a wide range of animals using a variety of techniques. 

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The first cloned fish -

In 1963, Chinese scientists reportedly created the first cloned fish by transferring the DNA from a male carp into the egg of a female carp.

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Dolly -

In 1997, scientists revealed that Dolly the sheep was the first mammal cloned from cells of an adult animal. She was born on July 5, 1996.

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The endangered ferret -

In 2021, scientists announced that for the first time they cloned an endangered American animal. It was a black-footed ferret named Elizabeth Ann, whose cells were taken from an ancestor.

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Why cloning? -

Reproductive cloning may enable researchers to make copies of animals with potential benefits for the fields of medicine and agriculture.

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Why cloning? -

For example, the researchers who cloned Dolly also cloned another sheep that was genetically modified to produce milk that contains a human protein essential for blood clotting. The hope is that someday this protein can be purified from the milk and given to humans whose blood does not clot properly.

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Other advantages of cloned animals -

Another possible use of cloned animals is for testing new drugs and treatments. The great advantage of using cloned animals is that they are all genetically identical, which means their responses to the drugs should be uniform.

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Cloning to bring back endangered animals -

Another argument to create clones is in order to build populations of endangered, or even extinct, species of animals. Although some experts think cloning can save many species, others argue that cloning produces a population of genetically identical individuals that lack the genetic variability necessary for survival.

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Cloned pets -

Some people also have expressed interest in having their deceased pets cloned. However, the cloned pet may not turn out exactly like the original whose DNA was used to make the clone.

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What are the potential downsides of cloning animals? -

Reproductive cloning is a very inefficient technique, and most cloned animal embryos cannot develop into healthy individuals. For example, Dolly the sheep was the only clone to be born alive out of a total of 277 cloned embryos.

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Possible disadvantages -

Researchers have found some health defects in cloned sheep and other mammals. These include an increase in birth size and a variety of defects in vital organs, such as the liver, brain, and heart. Other consequences include premature aging and problems with the immune system.

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Possible disadvantages -

Another potential problem centers on the 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 in the end dies.

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Possible disadvantages -

This is part of the natural aging process that happens 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 give the clones a shorter life span.

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Have humans been cloned? -

Despite several highly publicized claims, there currently is no solid scientific evidence that anyone has cloned human embryos.

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Claims of human cloning -

In 1998, scientists in South Korea claimed to have successfully cloned a human embryo, but said the experiment was interrupted very early when the clone was just a group of four cells.

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Further claims -

In 2004, a group of scientists from South Korea published a paper in a journal in which they claimed to have created a cloned human embryo in a test tube. However, an independent scientific committee later found no proof to support the claim. The scientific paper was later retracted.

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Issues with human cloning -

From a technical perspective, cloning humans and other primates is more difficult than in other mammals. This is because scientists remove the nucleus from the egg and replace it with the one from the donor cell. As it can take 100 or more tries with animals, there would be even more complications with humans.

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A ban on human cloning -

As of 2018, around 70 countries have banned human cloning. Cloning has been seen by many as controversial, and this is mainly due to the social, ethical, and religious implications.

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Arguments against cloning -

Critics of animal cloning typically argue that the cloning of pets could have bad consequences for the overwhelming numbers of unwanted companion animals. They also argue that animal cloning might cause health implications and pain for the cloned animal.

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Ethical issues -

Gene cloning is a carefully regulated technique that is largely accepted and used routinely in labs worldwide. However, it still raises ethical issues, as it may conflict with long-standing religious and societal values about dignity, individual freedom, identity, and autonomy.

Sources: (CNN) (National Geographic) (National Human Genome Research Institute) 

See also: The biggest science mistakes in movies 

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