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骡是马和驴子的后代。
马的染色体数是64条，驴的染色体数是62条，马的卵子染色体数是32条，驴的精子染色体数是31条，通过精卵结合发育成的新个体——骡子的染色体数是63条。骡子性成熟以后，再形成精子或卵子时，每条染色体都没有相对应的同源染色体进行配对，这样每一条染色体分到哪个配子里是随机的，就可能有马的1条染色体和驴的30条染色体形成一个配子，另一个是1条驴的染色体和马的31条染色体形成一个配子；再由马的2条染色体和驴的29条染色体形成一个配子，另一个是马的30条染色体和驴的28条染色体形成一个配子……依此类推，这样就可以产生232（接近429 500万）个不同类型的配子。在这些配子中，只有配子里的染色体完全来自于马的，或来自于驴的，这样的配子才有生育能力。
The horse and the donkey offspring
The chromosome number is 64 horse donkey, chromosome number is 62, the number of eggs in chromosome horse is 32, the number of sperm chromosome donkey is 31, the sperm egg binding chromosome number of new individual development into the mule -- is 63. After the mule sexual maturity, then form a sperm or eggs, each chromosome are not corresponding to the homologous chromosome pairing, so each chromosome to which gametes is random, 1 chromosomes and donkey might have a horse of the 30 chromosomes of a gamete formation, another is the 31 chromosomes 1 donkey and horse chromosomes form a gamete; then from 29 chromosomes of 2 chromosomes and donkeys and horses to the formation of a gamete, another is the 28 chromosomes of 30 chromosomes and donkeys and horses to the formation of a gamete...... And so on, so that you can produce 232 (close to 4295000000) different types of gametes. In these gametes gametes, only the chromosomes in completely from the horse, or from a donkey, gamete have fertility. |