What are the four main steps of fertilisation in humans

→ the sperm dissolves and penetrates any protective layer around egg reaching the cellular membrane → molecules on the sperm surface bind to receptors (specialised proteins) on the eggs plasma membrane to ensure both gametes are from the same species – sperm nucleus enters the egg → the surface of the egg changes so that no other sperm can enter → the eggs and the sperms nuclei’s fuse to form a zygote