When cloning an animal (sheep), if the cell donor is say, 3 years old, is the clone technically 3 years old?

Question

Or, is the clone "new."

Answer 1

Yes. An individual cell can undergo only a specified number of divisions. At the end of each chromosome is a chain of specialized DNA segments called telomeres. Each time the cell divides, one telomere is lost from the chromosome. This in effect causes the cell to "age", because each division brings the cell closer to the point when it can no longer divide - the end of its useful lifespan. If a cell that has already lost most of its telomeres is cloned, all the cells of the newly cloned animal will initially be missing the same number of telomeres as the cell used to produce the clone.

This is what happened with the first "successfully" cloned animal, the sheep called "Dolly". The cell from which Dolly was cloned came from a mature sheep, whose cells had already lost most of their telomeres. Therefore, cytologically Dolly was already "mature" at the moment of conception. As she continued to grow through cell division, she lost even more telomeres, so that by the time she was fully grown, a matter of a few months, her cells were already approaching the end of their normal lifespan. They were in effect "elderly". Therefore she died of "old age" shortly after that.

Answer 2

On the chromosomes (DNA) there is some "junk" sequence where the base pairs repeat in a certain pattern for an extended period. Say 1000 times (not actual number). These are called the telomeres. They have to do with cell age, and programed cell death.

Each time the cell divides this telomere or tail, gets shorter. After a while the cell recognizes it is too short, and is getting in danger of approaching DNA used in coding for gene products needed to run the cell. At this point the cell undergoes programed cell death. Or "Apoptosis".

When a clone is made from an adult cell, like "Dolly" the sheep. It used an adult cell that already had some of the telomeres used. The telomeres cannot be added to. Thus the "new" sheep created (cloned) came out at the same "cellular" age as the old one.

Answer 3

No, when an animal is cloned, it is born just like any other animal, and grows from a young animal to an adult. Although the clone does have the exact genome as the cell donor, phenotypic expression can still vary, and the clone may look nothing like the cell donor. For more information on this phenotypic difference, look up the case of the felines Rainbow and CC (copy cat).

Answer 4

It depends on who you ask. The cell itself may be relatively new, although the genetic material is not.

DNA strands have, on their ends, sections called "telomeres." A telomere is basically a section of DNA that doesn't do anything. But every time DNA replicates, the telomere is cut short. Eventually, the DNA runs out of worthless info and starts cutting into important stuff. Cut off enough important stuff, the DNA is useless, and the cell dies.

So if a strand of DNA is three years older than the cell it's in, it stands to reason that the telomere is also a bit older. Thus, the cell may die three years earlier. And a lot of cells dying three years early could mean that the animal dies a few years early, too.

Anyway, the animal's age is determined by when it's born. The DNA's age may be different, but that's not really what people pay attention to.

Answer 5

Most cells are replaced on a regular basis. Skin is replaced every few weeks. So the age of a cell has no bearing on the age of an organism.

Answer 6

It is "new"