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Post by JTF on Feb 23, 2008 8:52:34 GMT -5
Hello everyone! Science for some people is pretty easy, but for others it may be a bit difficult. So, for those people out there that need help or want to learn somthing new, I will be writing articles and posting links to websites to help you gain the knowledge to get that A average. I will try to write new articles about every month or so, but remember that you are not limited to learning from my articles. Create threads and ask away, but follow RULES!
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Post by JTF on Mar 1, 2008 18:42:47 GMT -5
Hello everyone! I decided to wait till March 1st to write the science article, so that everyone can have a whole month to look over things in this article.
Cell Growth and Division
Now as we all propbably know, cells reproduce. But why? There are two important things that you need to know about why they reproduce: 1. To make your body parts grow 2. And to replace damaged cells, such as in a wound. An adult human body produces about 2 trillion cells per day.
And, of course, there has to be a process behind the reproduction of cell. That is called mitosis
One thing that we must learn about before we go on is a chromosome Chromosomes, in eukaryotic cells, are structures in the nucleus of a cell which contain DNA and proteins. In prokaryotic cells, the chromosome is its main ring of DNA. DNA is organized into codes called genes, which contain the characters and traits that determine an organism's physical appearance and way of function.
Now, to make new cells a cell must go through mitosis. In mitosis a parent cell will divide into two identical daughter cells of equal size. There are four stages that cells must undergo to complete mitosis. Here I will list and explain each one:
1. Prophase: In this stage the chromosomes must first condense so as to not get tangled with each other, the nuclear envelope dissolves, and the chomosomes move to opposite poles of the cell.
2. Metaphase: During this stage the condensed chromosomes line up at the equator of the cell with the spindle fibers linking the chromatids to the opposite poles.
3. Anaphase: The spindle fibers then shorten which then pulls the chomatids to the opposite poles of the cell.
4. Telophase: During this final stage, nuclear envelopes form around each pole, spindle fibers dissolve, chromosomes uncoil, and Cytokinesis (the splitting of the cells) begins.
Eukaryotic Cell Cycle
The cell cycle is a repeating pattern of cellular growth and division during the life of a cell. The first portion of the cell cycle is Interphase, and the last is mitosis itself, but we have already covered that above. Interhase consists of three phases which I will list and describe below.
G1 (first gap phase): The cell grows very rapidly in this stage while building more organelles (the cells organs). A cell will spend most of its lifetime in this phase.
S (synthesis phase): The cell's DNA is copied and each chromosome consists of two identical chromatids which are attached at their centromere (the middle of the chromosome that links the sister chromatids together).
G2 (second gap phase): The last stage of Interphase. The cell continues to grow and prepares to divide.
Checkpoints
During the cell cycle, a cell goes through a process of inspection to make sure that the cell is ready to undergo the next phase.
There are three check points:
G1: This checkpoint is for the cell to check its surroundings. If its conditions and size are good then it is ready to move on to the next checkpoint. If not, then it enters a resting period.
G2: This checkpoint is for the cell to check for any mistakes in the copied DNA. If the cell passes this checkpoint, then it may start to divide. After this, proteins aid in the triggering of mitosis.
Mitosis checkpoint: This checkpoint occurs to make sure that the genetic material is distributed equally between the two daugter cells.
I Hope this article has shed some light on mitosis! Check back for more articles later! ;D
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Post by singingrain on Mar 6, 2008 23:07:50 GMT -5
cool idea! LOVE science...call me a nerd! lol my teacher showed us some pretty funny videos about mitosis on youtube! here's a link to a hilarious one: www.youtube.com/watch?v=JHRBJgq50dkIt's pretty educational and the song is just soo CATCHY!
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Post by singingrain on Mar 7, 2008 0:39:30 GMT -5
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Post by potatoparadox333 on Mar 9, 2008 19:52:50 GMT -5
the first video was a waste of a minute i will never get back. terrible haha. but the second video was pretty badass i have to admit
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