6.4.5 Natural Clones in Animals Flashcards
Does asexual reproduction occur in animals?
Asexual reproduction is much less common in animals than in plants
Some small animals reproduce asexually by parthenogenesis eg. aphids
The other naturally occurring incidence of cloning in animals is identical twins
How are identical twins formed?
An egg is fertilised by a sperm as in a singleton birth
This forms a zygote
The single zygote undergoes a few cell cycles (mitotic divisions) to become an embryo
This is why identical twins are referred to as monozygotic
At the embryo stage, the embryo splits in two; the exact causes of this kind of split are not well understood
Two embryos that form are identical, with the same genotype and develop in utero together
The result is the birth of identical offspring, always of the same gender, with identical phenotype
Because non-identical twins are formed from separate eggs and sperm, they are not considered clones
