the beginning of life

zygote earliest developmental stage humans anisogamous organisms formed egg cell sperm together create unique organism formation totipotent potential produce depends epigenetic reprogramming dna demethylation paternal genome appears important mouse sites methylated cytosines likely key process establishing totipotency involves processes base excision repair dna-repair–based mechanisms fertilized grow animal plant female39aph39s ovum male39aph39s join called aigenerated fertilization fertilize fusion item odd rare result zyg zygo acent anot batheed protiens fleids zygotein proteins fluids beginning life