Dolly the Sheep and the Science of Cloning
On July 5, 1996, a lamb named Dolly was born at the Roslin Institute in Scotland. She looked like an ordinary sheep, but the way she began life was extraordinary. Dolly was the first mammal cloned from a cell taken from an adult animal. Her birth showed that a specialized adult cell could help produce an entire new animal.
Dolly was not the first clone. A clone is an organism or cell with nearly the same genetic information as another. Clones can occur naturally: identical twins, for example, develop from the same early embryo. Scientists had also cloned animals from embryonic cells before Dolly. What made her different was the age and type of the cell that supplied most of her genetic information.
How Dolly was created
Most animal cells contain a nucleus, a structure that holds DNA. DNA carries instructions that help living things grow and function. As an animal develops, its cells become specialized for different jobs. A skin cell and a muscle cell generally contain the same DNA, but they use different parts of those instructions.
- specialized:
- Developed for a particular job or purpose.
- mammary gland:
- An organ in a mammal that produces milk.
- unfertilized:
- Not joined with a sperm cell.
- reconstructed:
- Put together again using different parts.
- uterus:
- The organ where a developing animal grows before birth.
- surrogate:
- An individual that carries a developing baby for another.
- euthanized:
- Put to death to prevent further suffering.
- consent:
- Permission given after a choice is understood.
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Preview questions from this passageShowHide
- 1How did Dolly differ from animals cloned before her?
- 2Why does the article compare skin and muscle cells before explaining Dolly's creation?
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About this explanatory article passage for Middle School
“Dolly the Sheep and the Science of Cloning” is a explanatory article reading passage about Animal cloning, written for Middle School. It takes about 4 minutes to read (563 words) and comes with an interactive quiz and a printable worksheet with comprehension questions and an answer key.