Reproduction 3: Fertilisation Flashcards
L4
What is fertilisation?
Union of 2 hapliod gametes, producing diploid offspring
Why is fertilisation not as simple as you might think? Give some examples of obstacles that occur.
- Sperm must make it to the ovum
- Gametes must recognise each other
- Sperm must penetrate ovum
- Haploid egg nucleus & sperm nucleus must fuse to from diploid zygote (syngamy)
- Ovum must block entry of additional sperm (polyspermy) to avoid polyploidy (pathologic in mammals) (>diploid)
List the structure of an egg cell
Germinal vesicle
Germinal spot
Ooplasm
Vitelline membrane
Zona Pellucida
Corona Radiata
What is the germinal vesicle in en egg cell?
nucleus containing DNA
What is the germinal spot in an egg cell?
nucleus
What is the ooplasm in an egg cell?
cytoplasm - contains nutrients
What is the Vitelline membrane in an egg cell?
cell membrane surrounding the ooplasm
What is the Zone Pellucida in an egg cell?
extracellular matrix containing glycoproteins
What is the function of the Zone Pellucida in an egg cell?
protects and plays vital role in fertilisation
What is the Corona Radiata in an egg cell?
layer of follicle cells
List the 4 structures of a sperm cell
- Head
- Neck - contains centriole
- Midpiece
- Tail / Flagella
Describe the head of a sperm cell
Contains nucleus with DNA, capped with acrosome
What does the sperm acrosome contain?
contains enzymes that help penetrate the egg membrane
Describe the neck of a sperm cell
contains centriole (important for tail formation and movement)
Describe the midpiece of a sperm cell
contains many mitochondria = energy for movement