Egg Cells Flashcards
What is the function of the egg cell?
To accept the genetic information delivered by sperm and then to implant into the uterus wall to initiate embryonic development.
How are egg cells produced?
Meiosis
What type of cell is an egg cell?
A gamete (reproductive cell)
What are the two roles of the zona pellucida?
1) It is very strong and therefore protects the inner nucleus
2) It is impermeable to sperm cells and needs to be broken down by acrosomal enzymes. Once a sperm cell breaches this layer the remaining zona hardens immediately to ensure only one sperm cell fertilises the egg.
What is the process of the sperm entering the egg?
1) Sperm binds to Zona Pellucida
2) Contents of the acrosome are released by exocytosis
3) The hydrolytic enzymes released help the sperm burrow through the Zona Pellucida, and enables binding +fusion of the sperm with the egg.
4) The sperm nucleus enters the egg cytoplasm
Why do egg cells have so many mitochondria?
For growth, DNA replication, Cell division, Protein synthesis
What happens to the Zona Pellucida after fertilisation? Why?
It hardens and becomes impermeable to stop anymore sperm getting fertilising it
How many sperm cells can fit across the diameter of an egg cell?
Sperm cell- 4 micrometres
Egg cell- 120 micrometres
= 30 sperm cells
