Science Class- Jan. 20-23

This week, there wasn't a lot that we did.  On Monday, we didn't have school, and on Tuesday I was watching the inauguration for most of the period, so we just asked questions about the test.  On Wednesday, we took the test, and on Thursday I think we discussed it a little bit.  On, Friday, we learned about mitosis at http://www.cellsalive.com/mitosis.htm.  

Mitosis is cell reproduction.  There are seven steps in mitosis.  They are interphase, prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis.  Interphase is when the DNA in the cell is being replicated.  Then, during prophase, the replicated DNA and proteins make the chromosomes.  The nucleus in the cell also starts to fade.  In prometaphase, the nucleus breaks down, and the spindle fibers get longer and attach to the chromosomes.  During metaphase, the spindle fibers cause the chromosomes to line up in the center of the cell.  Anaphase is when the spindle fibers get shorter, and the proteins on the chromosomes separate.  The chromatids, or replicated chromosomes, are pulled to opposite poles of the cell.  (The X shaped chromatids are split in half, and go to the poles.)  In telophase, the chromatids reach the poles, and the spindle fibers that are attached to the chromatids disappear.  Cytokinesis is when the spindle fibers that are not attached to chromatids start to break down, and form a section that separates the cell into two, and it forms two cells.  Then, both cells start interphase again, to prepare for more cell reproduction.