Animal Cloning Flashcards
(16 cards)
What is a clone?
Any cell/individual which is genetically identical to another.
What is natural animal cloning?
- common in invertebrates
- formation of mz twins (identical) - early embryo splits and forms 2 separate embryos -> genetically identical.
What is artificial cloning?
- reproductive cloning.
- involves creating a whole new animal that is genetically identical to another animal.
- uses TOTIPOTENT stem cells that is found in found in early embryo -> capable of forming any type of cell by differentiation.
What are the two main ways to generate clones by artificial cloning?
- artificial twinning
- somatic cell nuclear transfer.
What is artificial twinning?
After egg is fertilised -> forms ball of cells by dividing -> Totipotent -> potential to form whole new organism -> embryo becomes hallow ball of cells -> in this stage embryo can split into 2 (natural twins) -> can also be done artificially -> embryo manually split .
Describe process of artificial cloning in cows.
1- cow with desirable characteristics is treated with hormones (FSH) so she ovulates -> releases more mature ova than normal
2- ova fertilised naturally or by artificial insemination by bull with desirable traits -> early embryo flushed out of uterus gently
3- OR mature eggs removed and fertilised using semen in lab
4- (Totipotent) cells of early embryo splits -> produces several smaller embryos -> capable of forming full-term calf
5- each of the split embryos is grown in lab then implanted into surrogate mother -> each embryo implanted in diff mother -> single pregnancies have fewer risks
6- embryos develop into features -> born normally -> many identical cloned animals produced by diff mothers
Why are cows treated with hormones?
To make sure uterus lining is thick enough to accept embryos for implantation otherwise mother may miscarriage .
What is somantic cell nuclear transfer/reproductive cloning?
- used to clone adult.
- involves taking nucleus from an adult (somatic) body cells and transferring it to an enucleated egg cell (an egg cell that has had its nucleus removed)
- results in embryo being formed which is clone of original adult
What is the method for somatic cell nuclear transfer?
1- remove nucleus from adult somatic cell.
2- remove nucleus (enucleate) from mature ovum harvested from diff female animal of the same species.
3- nucleus from adult somatic cell placed into enucleated ovum using mild electric shock so it fuses and begins to divide
OR electrofusion occurs -> nucleus of adult cell not removed -> placed next to enucleated ovum and cell fuse + begin to divide from electric shock.
4- embryo transferred to uterus of 3rd animal
5- new animal is clone of animal which somatic cell comes from -> although mitochondrial DNA comes from egg cell.
Why is the new animal not fully genetically identical to original adult cell?
Mitochondria have DNA from egg cell.
What is the problem with this type of cloning?
Suffer from several diseases seen in older animal -> age faster rate as DNA had harmful mutations occurring overtime.
What are advantages of using artificial cloning?
Ad -
- artificial twining -> inc yielding from animals -> produce more offspring than usual
- artificial twinning -> results in multiple embryos -> embryos can be frozen -> used at later date as embryos are small and easily stored
- SCNT -> specific animals cloned (pets).
SCNT -> reproduction rate, endangered, extinct animals.
What are the disadvantages of using artificial cloning?
- SCNT -> inefficient -> not many successful cases -> takes too many eggs to produce a single successful cloned offspring.
- SCNT -> unsuccessful in increasing pop of rare organisms or bringing extinct species back.
- shortened life spans .
- many cloned embryos fail to develop properly -> miscarriage
What is therapeutic cloning?
- use of embryonic stem cells to generate tissues/organs for repair/ replacement
E.g. regeneration of heart muscle cells after heart attack - repair of nervous tissue - MS
- embryos usually come from surplus ones left over after IVF.
What are the ethics of therapeutic cloning?
AGAINST -> due to moral and religious grounds -> destroying potential human life.
FOR -> benefits outweigh this and argue that it would never have become a human life (destroyed).
What do they suggest for the future?
Re-program (expose to diff growth hormones/factors) differentiated adult cells to regain totipotent properties -> would be better source of stem cells as : unlikely to cause ethical concerns.
- stem cells could be produced from a person’s own body
- genetically identical to them so not likely to be rejected by immune system.
