Day 15 -April 6, 2009

Plenty has changed in the past three days!


I've grown a whole 3 centimetres taller! I'm already about 6 centimetres tall! My flowers won't bloom for another few days yet, but right now I'm undergoing meiosis. Meiosis is the process which makes my egg and sperm -- my gametes. They're also known as my "eggs" in my ovule and "pollen" in my microsporangium on my anthers. Meiosis has 8 stages, double the number of stages that mitosis goes through. Meiosis only ever occurs within germ cells, which, when maturity is obtained, begin this form of division. Meiosis increases genetic variation within species. It begins in Prophase I, when chromatin coils and duplicates, as well as lines up with it's homogulous chromosome begins to cross over. While doing such, the chromosomes are attached to the spindle fibre by their centromere and the nuclear membrane dissolves... From there, my germ cells go into Metaphase I where they are completely crossed over and beginning to separate. Then, in Anaphase I the homogulous pairs are ripped apart, completing crossing over and separating the cells. Then, just like in Mitosis, telophase it begins and separates the two cells. The cells are now haploid cells. Now, to create the gametes, the duplicated and crossed over chromatin is separated once again in the four steps. In the end, it creates 4 different cells instead of 1 duplicate, like mitosis. In addition, in my ovule, only 1/4 gametes created will function, as the other 2 gametes from each germ cell will die in order to contribute all of their nutrients to the egg in order to make it function very well. That's meiosis! B. Rapa
P.S. What to learn more about meiosis? Here's a link to a wonderfully catchy song AND helpful song that my gardener's biology teacher displayed: http://www.youtube.com/watch?v=iCL6d0OwKt8

Gametes: The sperm and egg. Haploid cells used in reproduction, they originate from the germ cells.

Ovule: The female sex organ on a plant which holds the female gametes.

Microsporangium: Pouches on the anthers that hold pollen.

Anthers: The highest male point of a flower, they support pouches which hold pollen (See: MICROSPOANGIA above)

Cross over: The process in which homogulous cells cross over in order to increase genetic variety.

Haploid: A state of a cell with HALF of the original chomorsomes, i.e. gamete.