What is in a pollen grain
2x haploid nuclei:
1x tube nucleus
1x generative nucleus
What is in an ovule sac?
1x ovum
3x antipodal cells
2x polar nuclei
2x synergids (helps generative nucleus from PG reach ovum)
1x outer protective coating
Gametogenisis in plants
How does the male nuclei reach the embryo sac
The pollen grain lands on stigma.
The pollen grain germinates (grows) and secretes hydrolytic enzymes to digest tissue of the style. This is controlled by tube nucleus.
Generative nucleus undergoes mitosis to produce 2 male gamates which enter embryo sac.
What happens in double fertilisation
Zygote forms when 1 male gamete and ovum fuses.
Triploid endosperm (food source for zygote) forms when 1 male gamete and 2 polar nuclei fuse.
Gametogenisis in humans
Fertilisation in humans
Last changeda year ago
