Fertilisation

Question 1

ACROSOME REACTION

Answer 1

1. Sperm reaches the ovum
2. Chemicals are released from the ovum (trigger cascade)
3. Acrosome in sperm head swells and fuses with the sperm cell membrane
4. Hydrolytic enzymes are released and digest through the follicle cells and zona pellucida
5. Sperm cell membrane fuses with egg cell membrane
6. Sperm nucleus enters egg cell
7. Nuclei fuse

Question 2

CORTICAL REACTION

Answer 2

1. Lysosomes in egg cell migrate to egg cell membrane
2. Lysosomes fuse with membrane and release chemicals into the zona pellucida (exocytosis)
3. Zona pellucida hardens to prevent polysperming

Question 3

Describe the effect of MEIOSIS on the chromosome number

Answer 3

Beginning = full number of chromosomes
End = half number