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Sunday, July 19, 2009

Bio lesson

Okay...Bio exam....chapter 5 and 6 coming out...4got got include chapter 4 or not...
Anyway, since chapter 4, i did not understand or even try to understand a single word teacher was teaching...lol...
I mean...I dunno what it's all about...
So now I'm going to run thru it...
Chapter 5: Cell Division
Do I know what is Mitosis?
I think it's a process.
*checks book*
haiya kira betul la...mitosis o...is a type of cell division.
Nucleus > 2 daughter cells (same number+type of chromosomes as the parent cell
This mitosis o...(what a name!)...occurs in all the SOMATIC CELLS (ok la I just wanted to rmbr)...
btw, somatic cells are all the body cells, except 4 gametes.
apa tu gametes btw?
Oh no I'm so teruk!
Ok la...go on...the somatic cells ada 2 sets of chromosomes...one is from the mama and the other from the papa cell. These kind of somatic cells are called diploid cells. 2n.
The cells that hv only one set of unpaired chromosomes o...they are called haploid cells.
hmm. n.
All the gametes are haploid.
oic.
In us o...manusia o...each somatic cell has 46 chromosomes or 23 pairs of chromosomes.
wow.
In mitosis, somatic cell will divide, then produce 2 diploid cells that r same with the parent cell.
The significance of Mitosis:
a) In multicellular organisms, this mitosis o, it will produce new cells for growth, repair and replace cells that are dead or damaged. means, I think, almost the same as protein lo. Then I no need drink milk also can liao o. jk jk
b) In unicellular organisms, the mitosis is a from of asexual reproduction to increase the number of organisms. oic!!! mitosis is also reproduction. @_@ getting increasingly blur...
c) Mitosis ensures that the offsprings are genetically identical to the parent. Almost like clone hor.
d) It also preserves the diploid number of chromosomes. whatever this means.

The Cell Cycle
Got 2 phases...interphase and mitotic phase (M phase)
When the mitotic phase berlaku o, there is mitotic cell division. bao kuo mitosis and cytokinesis.
Sucessful mitotic cell divisions alternate with the interphase.
The M phase is very short de...in fact is the shortest part of the cycle (useless lo..like that short ppl=.=)...then the interphase is about 90% of the cycle...means long de...means like his fren...means good...^^
Interphase can split into 3 subphases:
a) G1 phase (1st gap)
b) S phase (synthesis)
c)G2 phase (2nd gap)
When G1 and G2, the cell grows by producing proteins and cytoplasmic organelles. Cell growth and cell differentiation occurs.
In the S phase, occurs synthesis of DNA. Chromosomes duplicate, and DNA replicates to form 2 identical sister chromatids, joined 2gether with centromere. wow so fu zha~!
During interphase, the chromosomes are invisible...like my bf, and they appear as thread-like structures, panggil them chromatin.
Interphase o, involves synthesis of protein+organelles, growth, replication of DNA, cell differentiation, storage of energy. wah.
On the other hand, mitotic phase.
Nucleus divides during mitosis, after that division of cytoplasm, called cytokinesis. then produce 2 daughters.
Interphase complete liao jiu hui mitosis.

ei...SIEN la...continue another day...

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