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Title: Why is it impossible for two sperm or two eggs to fuse or create a zygote? Post by: SoTired67 on Aug 28, 2021 Given that in all species, humans included, from non-mammalian to mammalian, only sperm and egg can fuse or create a zygote, and two sperm or two eggs can not, as in it is impossible for two sperm or two eggs to fuse, or create a zygote, I have been wondering why that is the case.
It's fascinating that two sperm or two eggs can not fuse or create a zygote (not getting into why I think it should stay that way, because that's a whole other topic). Egg and sperm are both haploid. Eventhough an egg (a haploid) can fuse with a sperm (a haploid), a sperm (a haploid) can not fuse with another sperm (a haploid), and an egg (a haploid) can not fuse with another egg (a haploid). Why? What makes it so two sperm or two eggs can not fuse despite being haploid? Why isn't being haploid enough for fusion? My question is, what (biological) processes/mechanisms are there that make it impossible for two sperm or two eggs to fuse or create a zygote? Why is it that only sperm and egg can fuse or create a zygote? And what are these processes/mechanisms called? I've heard there are certain proteins. What proteins are they? Title: Re: Why is it impossible for two sperm or two eggs to fuse or create a zygote? Post by: bio_man on Aug 29, 2021 Sperm lack the cellular mechanisms required for cell division; they don't contain the nutrients and organelles that the egg is designed to have for replication to occur. So even if you were able to form a diploid cell by combining the genetic material from two sperm, it would not be able to replicate.
A group in 2004 did manage to get two female mice to have a pup. But to do this, they had to tweak one mom’s DNA to make it more male-like. And it wasn’t terribly efficient - it took 457 tries to get a healthy pup. Source: [1] (https://genetics.thetech.org/node/89) Title: Re: Why is it impossible for two sperm or two eggs to fuse or create a zygote? Post by: detimo on Aug 29, 2021 That's correct, sperm are not packed with the organelles needed for division to occur. Sperm are filled with mitochondria and sugar needed to generate energy to meet the egg, while the egg contains the rest of nutrients to nurture the zygote. In fact, the first several divisions are done with only the nutrients contained in that initial fusion
Title: Re: Why is it impossible for two sperm or two eggs to fuse or create a zygote? Post by: SoTired67 on Sep 22, 2021 Sperm lack the cellular mechanisms required for cell division; they don't contain the nutrients and organelles that the egg is designed to have for replication to occur. So even if you were able to form a diploid cell by combining the genetic material from two sperm, it would not be able to replicate. A group in 2004 did manage to get two female mice to have a pup. But to do this, they had to tweak one mom’s DNA to make it more male-like. And it wasn’t terribly efficient - it took 457 tries to get a healthy pup. Source: [1] (https://genetics.thetech.org/node/89) I clicked on the source and it said I'm not authorized to access the page. Could you copy-paste the content, or share a screenshot of the content please? Title: Re: Why is it impossible for two sperm or two eggs to fuse or create a zygote? Post by: bio_man on Sep 22, 2021 It looks like they took it down :-\ I only referenced the article, but had I copied the direct quote, I could find another source.
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