Clone facts for kids

A clone is like an exact copy of something else. In biology, cloning is a way to make one or more living things that are genetically identical. This means they have the exact same DNA as the original. Think of it like making a perfect photocopy of a living thing!

The most famous example of cloning a mammal was Dolly the sheep. She was the first mammal cloned from an adult cell. Did you know that Human identical twins are actually natural clones? They start from the same original cell and split, making them genetically identical. Some animals also reproduce naturally by cloning, like when a plant grows a new plant from a cutting.

What is Cloning?

Cloning means creating an exact copy. In science, it usually refers to making a copy of a cell, a piece of DNA, or even a whole living thing.

For example, when scientists talk about cloning DNA, they mean making many identical copies of a specific DNA sequence. This is very useful for studying genes.

When a cell divides, it usually makes two identical "daughter" cells. These are also clones of the original "mother" cell. However, as living things grow, cells change and become specialized for different jobs (like skin cells or muscle cells). These specialized cells are still derived from the original cell, but they aren't exactly identical anymore because their genes are working differently.

Natural Clones

Cloning happens naturally in many ways. For instance, Human identical twins are natural clones. They form when a single fertilized egg splits into two, creating two babies with almost identical DNA.

Some animals also clone themselves naturally. For example, the nine-banded armadillo usually gives birth to identical quadruplets. This means four babies that are all natural clones of each other!

Another way natural cloning happens is through asexual reproduction. This is when an organism creates offspring without needing a partner. The offspring are exact genetic copies of the parent.

Not Quite So Identical

Even though clones start off as exact copies, they might not stay that way. For example, Identical twins always end up looking and acting slightly different.

Small Genetic Changes

A study in 2012 looked at 92 pairs of identical twins. It found that even identical twins get hundreds of small genetic differences very early on. These changes happen because of tiny mistakes (called mutations) in their DNA as they develop. On average, identical twins might have about 360 genetic differences from these early changes. However, these small changes usually don't make a big practical difference. Identical twins still look and behave very similarly.

Environmental Differences

Another reason for differences between identical twins is something called epigenetic modification. This means that even with the same DNA, different things in their environment can affect which genes are "switched on" or "switched off."

Imagine a light switch for a gene. The gene is there, but whether it's working depends on the switch. Environmental factors like diet, lifestyle, or even stress can flip these switches.

A study of 80 pairs of identical twins, from ages three to 74, showed this clearly. Younger twins had very few epigenetic differences. But as they got older, the number of differences grew. Fifty-year-old twins had over three times more epigenetic differences than three-year-old twins. Twins who grew up apart, like those adopted by different families, had the biggest differences. This shows how much our environment can influence us, even if we start with the same genetic blueprint.

Species Cloned by Scientists

Scientists have successfully cloned many different animal species in the laboratory. Here are some examples:

• Carp: (1963) In China, a scientist named Tong Dizhou made the world's first cloned fish. He put DNA from a male carp's cell into an egg from a female carp.
• Mice: (1986) A mouse was the first mammal cloned from an early embryo cell. Soviet scientists cloned a mouse named "Masha."
• Sheep: (1996) The famous Dolly the sheep was cloned in 1997 from an adult cell. Before Dolly, other sheep like Megan and Morag were cloned from embryonic cells in 1995.
• Monkey: (2000) Tetra was cloned from embryo splitting.
• Gaur: (2001) This was the first endangered animal species to be cloned.
• Cattle: Alpha and Beta males were cloned in 2001 and 2005 in Brazil.
• Cat: CopyCat "CC" (a female, late 2001) was the first cloned cat. Little Nicky (2004) was the first cat cloned for commercial reasons.
• Dog: (2005) Snuppy, a male Afghan hound, was the first dog to be cloned.
• Rat: (2003) Ralph was the first cloned rat.
• Mule: (2003) Idaho Gem, a male mule, was the first animal from the horse family to be cloned.
• Horse: (2003) Prometea, a female Haflinger horse, was the first horse clone.
• Water Buffalo: (2009) Samrupa was the first cloned water buffalo. She was born in India but sadly died a few days later from a lung infection.
• Camel: (2009) The first camel was cloned.
• Crab-eating macaque: (2018) This was the first time scientists cloned any ape or monkey using cells from an older donor, not just an embryo.