Topic 22 - Reproduction and Development

Question 1

Learning Outcomes

Answer 1

1. Describe the process and function of meiosis.
2. Explain the functions of organs in the male and female reproductive system.
3. Compare differences between oogenesis and spermatogenesis.
4. Describe the regulation of reproduction by the hypothalamic-pituitary-gonadal axis in males and females.
5. Explain the role of gonadal hormones in males and females.
6. Describe the process of fertilization and preimplantation embryo development.

Question 2

Meiosis 1

Answer 2

(I, PMAT)

Interphase:
- G1, S, G2

Prophase (2n= diploid cell):
- Centrioles to poles
- Nuclear membrane breaks down
- Chromosomes condense
- 23 pairs of chromosomes bind to another 23 to form 46 homologuous pairs

Metaphase:
- Chromosomes line up at equator
- In meiosis crossing over occurs to form genetic variability

Anaphase:
- Sister chromatids are pulled by spindle fibres

Telophase:
- 2 sets of chromosomes at each pole
- Nuclear membrane starts to form around the 2 sets
- Cytokinesis starts to appear

Identical diploid daughter cells form

Meiosis 2 Starts

Question 3

Meiosis 2

Answer 3

Interphase:
- Growth only

Prophase 2:
- Nuclear membrane breaks down
- Spindle fibres form
- Centrioles to poles
- Chromosomes condense

Metaphase 2:
- Chromosomes line up at the equator as single chromosomes

Anaphase 2:
- Chromatids move to poles by pulling of spindle fibres

Telophase 2:
- Nucrear membrane forms around 2 sets of chromosomes

4 haploid cells produced in the end

Question 4

Female reproductive system [heft]

Answer 4

[heft]

Question 5

Male reproductive system [heft]

Answer 5

[heft]

Question 6

Spermatogenesis

Answer 6

1. Spermatogonia (2n) undergo repeated mitosis to create more spermatogonia and primary spermatocytes
2. Some spermatogonia begin differentitation and undergo meiosis 1 to create secondary spermatocytes
3. Secondary spermatocytes undergo meiosis 2 to produce spermatids
4. In the seminiferous tunules the spermatids develop into sperm with support of sertoli cells

Question 7

Oogenesis

Answer 7

[heft]

Question 8

Male Hormones before pubity

Answer 8

• Hypothalamus and anterior pituitary gland are immature
• Hypothalamus releases GnRH into pituitary gland
• GnRH stimulates production of FSH and LH from pituitary gland
• Testosterone is produced by interstitual cells in testes and has a negative effect on Hypothalamus and pituitary due to immature
• GnRH is inhibited by the negative feedback loop
• Sertoli cells secrete inhibin with testosterone

Question 9

Male hormones after pubity

Answer 9

• Hypothalamus and pituitary mature
• Testosterone has a positive feedback loop on sertoli cells and sperm development

Question 10

Hormones in females before pubity

Answer 10

• Same process as male but eostrogen and progesterone instead of testosterone
• Ovaries instead of testes