It was a bad week in science this week. We had a sub twice in the week and I was absent one of the days the sub was there. We continued with mitosis this week. We talked about how chromosomes change during mitosis and a cell's life. They start as chromatin, and unwoung mess of DNA in the nucleus. Then it condences into a chromosome. Then the chromosome is copied and conected to the copy at a kinetacore. The two chromosomes individualy are now called chromatids, while together they are a chromosome. Then when the two chromatids separate during anaphase of Mitosis, they are each chromosomes again. And in telophase when two nuclei are formed they unwind into chromatin again.

We then learned about the cell cycle. It has four stages. Gap 1, Syntesis, Gap 2, and Mitosis. In Gap 1 the cell does regular things like making protiens and growing. At the end of Gap 1, the cell checks if all the conditions are right to reproduce. If not, it repeats Gap 1, if the conditions are right it moves to synthesis. In synthesis the cell copies all the DNA in it's nucleus. Then it moves to Gap 2 where it grows more in preporation to Mitosis, and it makes any protiens it will need in Mitosis. Now the cell moves to Mitosis where it splits apart to form two daughter cells. Then the cell cycle starts over with Gap 1 in both cells. The lenth of the full cycle varies for different types of cells. A skin cell might take 8 hours to go through the cycle, but a heart cell could take 45 years.

We learned about how much time a cell spends in each phase, Interphase, Prophase, Metaphase, Anaphase, and Telophase. 56% of it's time is in Interphase, 28% in Prophase, 8% in Metaphase, 6% in Anaphase, and 3% in Telophase. So if it takes a cell 24 hours to go through all these, 13.44 hours are spent in Interphase, 6.72 hours in Prophase, 1.92 hours in Metaphase, 1.44 hours in Anaphase, and 0.72 hours in Telophase.