THE LEGACY OF DOLLY THE SHEEP
Milja Tomašević
Konstantin Grujić
Milica Sumzer
DNA
DNA is a polymer built out of two polynucleotide chains. They together form a helix like stucture.
There are 4 different nucleotides in DNA, adenine , guanine , cytosine and thymine.
They pair up adenine with thymine and guanine with cytosine.
DNA contains the instructions needed for an organism to develop, survive and reproduce. DNA carries genes which are basically recepies for our proteins and other information about ourselves. When a cell divides, DNA must be replicated in order for both of the new cells to recieve the same amount of DNA.
Cloning in general
Cloning is a technique scientists use to make exact genetic copies of living things.
After all this time, we have cloned genes, cells, tissues, and even whole animals.
Organisms can be cloned in one of two ways: artificial embryo twinning and somatic cell nuclear transfer.
Two types of cloning
As the name suggests, this technique mimics the natural process that creates identical twins.. A very early embryo is separated into individual cells, which are allowed to divide and develop for a short time in the Petri dish.
Artificial embryo twinning
Somatic cell nuclear transfer
Somatic cell nuclear transfer (SCNT), also called nuclear transfer. A somatic cell is any cell in the body other than sperm and egg.
The history of cloning
1885 - First-ever demonstration of artificial embryo twinning
1902 - Artificial embryo twinning in a vertebrate
1928 - The cell nucleus controls embryonic development
1952 - First successful nuclear transfer
1958 - Nuclear transfer from a differentiated cell
1975 - First mammalian embryo created by nuclear transfer
1984 - First mammal created by nuclear transfer
1996 - Nuclear transfer from laboratory cells
1996 - Dolly: First mammal created by somatic cell nuclear transfer
A little about Dolly’s life
Dr. Ian Wilmut, Keith Campbell and many more scientists decided to clone a sheep from an adult embryo.
After 277 unsuccessful tries, one embryo - 6LL3, later named Dolly survived.
She had three mothers and was born on 5. July 1996.
She lived half the age most sheep do.
She died on 14. February 2003.
She is currently on display in a museum.
They still have not cloned a human, though. In part, this is because it is difficult to produce a viable clone. In each attempt, there can be genetic mistakes that prevent the clone from surviving.
At the time she was one of the biggest scientific acomplishments
How they cloned a sheep
1. Scientists took udder cells from Dolly’s DNA mother. They let the cells multiply and then they stopped the process when they had divided enough.
2. They took an egg cell from a different sheep and removed the nucleus.
3. They put one udder cell next to the egg cell without a nucleus and joined them using electricity. The egg cell now contained all the udder cell’s DNA.
4. The egg cell divided until it developed into an embryo.
Cloning in the future time
Cloning of endangered species may become common place as we try to preserve our planets biodiversity.
We may even be able to clone extinct species, and bring them back into existence.
We might be cloning our pets in the future instead of getting “new” ones.
In conclusion
Cloning may become one of the most important scientific fields in this century as its potential is fully unraveled.
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