Topic 2 - gametogenesis in mammals + fertilisation

Question 1

List the key cells in spermatogensis

in order

Answer 1

• primordial germ cell
• spermatogonia
• primary spermatocyte
• secondary spermatocyte
• spermatid
• spermatozoa

Question 2

how does a spermatid differentiate into a spermatozoa

Answer 2

tail, acrosome, midpiece, many mitochondria

Question 3

what is the tale of a sperm cell called

Answer 3

undilipodium

Question 4

what do sperm cells need mitochondria

Answer 4

allows the undilipodium to rotate, which moves the cell

Question 5

List the key cells in Oogenesis

Answer 5

• primordialgerm cell
• oogenia
• primary oocyte
• secondary oocyte
• ootid
• mature ovum
• polar bodies

Question 6

how many polar bodies are produced in oogenesis

Answer 6

4

Question 7

what happens to polar bodies

Answer 7

• degenerate and die

Question 8

Exam questions

Describe how the products of oogenesis differ from the products of spermatogenesis in mammals (4)

Answer 8

Ova are larger cells (1) and are surrounded by the zona pellucida (1). Spermatozoa contain an acrosome (1) and have a flagellum (1), ova do not. Oogenesis produces polar bodies (1), spermatogenesis does not

Question 9

Describe the process of Mammalian fertilisation

Answer 9

• sperm head contacts with the zona pellucida and an acrosome reaction occurs -> digestive enzymes break down the zona pellucida (as acrosome fuses with cell membrane if sperm + releases digestive enzymes)
• sperm head fuses with cell membrane of egg cell -> allows sperm nucleus to fuse with egg cell’s
• cortical reaction occurs -> hardens zona pellucida to avoid polyspermy
• nuclei fuses - full set of chromosomes restored forming diploid zygote

Question 10

parts of the ovum

Answer 10

• zona pellucida -> protective coating sperm penetrates
• haploid nucleus
• cortical granuel -> release substances, to harden zona pellucida
• follicle cells -> forms protective coating atound egg