22.3 Cloning in animals Flashcards
How does natural cloning usually occur in invertebrates? (1 mark)
Regenerate from fragments of original.
How does natural cloning usually occur in vertebrates? (1 mark)
Monozygotic (identical) twins.
What is artificial twinning? (1 mark)
Cloning an embryo through imitating the way twins are produced.
Explain how artificial twining is done. (5 marks)
- Cow is treated with hormones so releases more ova than normal.
- Ova fertilised naturally or artificially (insemination) an early embryos gently flushed out of uterus OR mature eggs are removed and fertilised in lab.
- Around day 6 (cells are still totipotent), the cells of the early embryo are split to produce several smaller embryos.
- Each split embryo is grown in a lab for a few days, then implanted into a surrogate mother
- Embryos develop into foetuses and born normally
What does SCNT stand for? (2 marks)
Somatic Cell Nuclear Transfer Cloning
What is SCNT? (1 mark)
When an adult animal is cloned.
Explain how SCNT is done. (4 marks)
- Nucleus removed from a somatic (body) cell of an adult animal.
- Nucleus is removed from a mature ovum harvested from a different female animal of the same species (it is enucleated).
- The nucleus from the somatic cell is placed into the enucleated ovum and given a mild electric shock to fuse them.
- The embryo that develops is transferred to a surrogate mother.
Give two problems with cloning. (2 marks)
Born abnormally large
Health problems
What is non-reproductive cloning, and what is it used for? (2 marks)
Clones cells, used to study cells, tissues, and organs.
Give four arguments for cloning. (4 marks)
Artificial cloning:
High yielding
Success of a sire at passing on desirable traits
SCNT:
Can clone specific animals
Potential to clone endangered/ extinct animals
Give three arguments against animal cloning. (3 marks)
SCNT:
Inefficient process- often multiple eggs are used to form one clone
Many cloned embryos miscarry/ produce malformed offspring
Clones have shorter lifespans
