The biology of the cell

Question 1

What is the Zona pellucida and what does it do?

Answer 1

ZP is a glycoprotein layer that protects the oocyte and prevents inter-specie fertilisation

Question 2

What are cortical granules and what do they do?

Answer 2

Cortical granules are vesicles that sit on the basement/plasma membrane of the oocyte. Once the egg has been fertilised they are released to prevent polyspermy from occuring

Question 3

What are corona radiata and what do they do?

Answer 3

They are the inner most layer of the culumus that surrounds the oocyte. They supply proteins to the oocyte.

Question 4

Describe the shape and components of sperm

Answer 4

• Head with inactive DNA
  -Acrosome vesicle surrounding head
• tail/ axoneme (flagellum)

Question 5

Describe the three sections of the sperm tail

Answer 5

• Middle piece containing specialised mitochondria
• principle piece
• end piece

Question 6

What is the sperm axoneme?

Answer 6

Core structural component of tail/flagellum

Question 7

Describe the acrosomal reaction?

Answer 7

When hydrolytic enzymes are released from the acrosomal vesicle to help the sperm penetrate ZP

Question 8

Describe why the sperm DNA being highly condensed is important.

Answer 8

• More compact due to protamines rather than histones
• highly condensed = lighter = move faster
• genetic expression completely absent
  -protects DNA from oxidative stress