Fertilisation Flashcards
Define fertilisation
Fertilisation occurs when the nucleus of the sperm fuses with the nucleus of the egg, forming a diploid zygote
Why do many of the sperm die in the female system?
2
Due to the acidic conditions in the vagina
Due to being attacked (as foreign objects) by white blood cells in the female system
Other than being killed by acidic conditions or wbcs why do some sperm not reach the egg?
The enter the wrong fallopian tube (the one not containing the egg)
How do sperm get through the membrane of the egg?
The acrosomes at the front of the sperm contain enzymes that are used to digest an opening through the membrane of the egg
How many sperm fertilise the egg?
Just one even though many will reach the egg
What happens when the firs sperm reaches the egg?
It loses its tail and its head enters the egg
What happens once the sperm has entered the egg?
The membrane of the egg undergoes a rapid chemical change which forms a fertilisation membrane which prevents further sperm from entering
What is the function of the fertilisation membrane?
It prevents further sperm from entering the egg
Once the egg has been fertilised, what happens to the egg?
It undergoes a rapid chemical change which forms a fertilisation membrane which prevents further sperm from entering
What prevents further sperm from entering the fertilised egg?
The fertilisation membrane
What happens to the sperms tail when it reaches the egg?
Only the head enters the egg (the tail is left outside)
How long does the egg survive without being fertilised?
For up to 2 days
For how long can the sperm live?
They can survive for up to seven days
Why can the sperm live for up to seven days in the female reproductive system?
Because they are nourished in the female reproductive system
Sperm can survive for seven days in the female reproductive system, what benefit does this have?
It increases the chance of fertilisation
