Bio germination

RuehlTheWorld

Can someone explain the development of the pollen grain and ovule and embryo sac and all that? And rather simply? I'm good with plants bar this.

Thanks a mil

christina_x

RuehlTheWorld wrote: »

Can someone explain the development of the pollen grain and ovule and embryo sac and all that? And rather simply? I'm good with plants bar this.

Thanks a mil

formation of male gametes:
anther is made up of four chambers called pollen sacs.
each pollen sac has a layer of diploid cells called microspore mother cells.
microsposre mother cells divide by meiosis to for a group of four pollen cells called a tetrad.
tetrad splits apart to form four individual pollen grains.
immature pollen grains = microspore.
each has a haploid nucleus
halves my mitosis to form 2 haploid nuclei. one of these does not divide any more (tube nucleus) and the second (generative nucleus) divides my mitosis to form two sperm nuclei. these are the male gametes

female gametes
each ovule has two walls called integuments. small openings in integuments called mycropyle, where the pollen tube can enter the ovule.
bulk of ovule consists of diploid nourishing cells = nucellus
megaspore mother cell is a single diploid cell in centre of ovule which divides by meiosis to for embryo sac which contains 4 haploid nuclei. 3 of these die. the 4th divided by mitosis 3x to form 8 haploid nuclei
one beecomes egg nucleus which fors egg celll. the other 2 become polar nuclei (other 5 die off)
egg cell + polar nuclei are femate gametes


hope thats helpful!

RuehlTheWorld

That's fantastic really to the point, thanks so much!

Good luck next week!