Component 2.3 - gametogenesis

Question 1

Describe the head of a sperm?

Answer 1

1) Contains a haploid nucleus

2) Covered by a lysosome called the acrosome, which contains enzymes used at fertilisation

Question 2

Describe the middle piece of a sperm

Answer 2

It is packed with mitochondria which provide ATP for movement.

Question 3

What is meant by ovulation?

Answer 3

Where a primary follicle develops into a secondary follicle (Graafian follicle when it is mature). Migrated to the surface of the ovary where it bursts and releases the secondary oocyte.

Question 4

Describe oogenesis before fertilisation

Answer 4

1) Germinal epithelium (2n) undergoes mitosis forming oogonium and more germinal epithelium
2) oogonium (2n) undergoes mitosis forming primary oocytes and more oogonium
3) Primary oocyte (2n) completes meiosis 1 forming a secondary oocyte (n) and the first polar body (n)
4) Secondary oocyte begins meiosis 2 but stops at metaphase 2

Question 5

What stage of oogenesis are you at when you are born?

Answer 5

A girl is born with millions of primary oocytes at prophase 1

Question 6

What happens in oogenesis after fertilisation takes place?

Answer 6

1) Meiosis 2 is completed making an ovum (n) and a second polar body (n)

Question 7

Describe spermatogenesis

Answer 7

1) Germinal epithelium (2n) divide by mitosis forming spermatogonium (2n) and more germinal epithelium
2) Spermatogonium divide by mitosis forming primary spermatocytes (2n) and more spermatogonium
3) Primary spermatocytes under meiosis 1 and meiosis 2, forming secondary spermatocytes (n) and spermatids (n) respectively
4) spermatids mature into spermatozoa