Eli5: How does a microscopic sperm after fertilization can form so many complex Organs and chemicals, as atoms can’t be created nor destroyed? Also if neurons can’t divide, how did it came into existence in the first place?

Question

Eli5: How does a microscopic sperm after fertilization can form so many complex Organs and chemicals, as atoms can’t be created nor destroyed? Also if neurons can’t divide, how did it came into existence in the first place?

In: Biology

Answer 1

Atoms can be created and destroyed, but fortunately high-energy nuclear physics isn’t happening in your mom.

The atoms in you are instead scavenged from food and repurposed.

The sperm and egg cells contain what’s essentially an instruction manual for how to build a human. The fertilized egg cell then begins to follow that manual, procedurally generating a human from the instructions using materials the mother gets from her meals.

The finished adult nerve cells are highly specialized and do not divide or repair themselves easily or often, but during the early stages of development more generic “stem” cells build the nervous system. Once the system is closer to completion, they divide one final time and create the finalized less malleable neurons.