So I know that an egg cell and a sperm cell are each haploid (with 23 chromosomes and 23 chromatids). Then when they fuze they create a diploid zygote with 46 chromosomes. But when are the chromatids of each chromosome duplicated?
Once the sperm and egg meet they continue with meiosis II. Remember the egg stopped at Prophase I of meiosis. Ovulation completed Meiosis I and once the egg and sperm join it continues with Meiosis II the duplication portion. Am I correct? Anyone?
I think you have things confused. There is no "duplication portion" in meiosis II. When the egg and sperm fuze they have each gone through meiosis II and are haploid with 1 chromatid on each chromosome. The zygote is diploid, but i think each chromosome still had only 1 chromatid. so my question is, when do the chromosomes duplicate their chromatids?