Lecture Notes on Cloning and Dolly the Sheep

Introduction to Cloning

• Dolly, the most famous sheep, was the first mammal cloned from an adult somatic cell.
• Cloning refers to creating genetically identical organisms.
• Clones: Organisms with identical genetic information.

Types of Reproduction

• Asexual Reproduction:

  • Organisms create genetically identical copies without sexual reproduction.
  • Example: Bacteria replicate their genome and divide via binary fission.

• Sexual Reproduction:

  • Involves the combination of genetic material from a male (sperm) and female (egg).
  • Each parent contributes one copy of genetic information.

Dolly's Creation

• Dolly was created through artificial cloning in 1996.
• She did not have biological parents in the traditional sense.

Cloning Process

1. Egg Cell Donor (Sheep 1):

   • Scottish Blackface sheep provided the egg cell.
   • The nucleus was removed, leaving an egg cell without DNA.

2. Somatic Cell Donor (Sheep 2):

   • A different sheep’s somatic cell had its nucleus isolated, containing the full genetic blueprint for Dolly.

3. Nuclear Transfer:

   • The isolated nucleus from Sheep 2 was transferred into the enucleated egg cell from Sheep 1.
   • Resulted in a hybrid cell.
   • An electric stimulus triggered cell division, leading to the blastocyst stage.

4. Surrogate Mother (Sheep 3):

   • The blastocyst was implanted into a Scottish Blackface sheep (Sheep 3), serving as a surrogate.
   • Dolly was born with genetic material identical to Sheep 2, not resembling Sheep 3.

Dolly's Life

• Lived for almost 7 years.
• Successfully gave birth to progeny.

Conclusion

• Dolly's cloning was a significant scientific achievement demonstrating the possibilities of cloning technology.

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