Mitosis
Mitosis Steps Summary
This is a summary of Mitosis from the University of Arizona. Mitosis Power Point form NIU This is a power point about mitosis that I found helpful from Norther Illinois Universtiy.
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Mitosis VideosMitosis Animation
This is a cool Mitosis animation from Cellsalive.com |
Mitosis Notes
mitosis.docx | |
File Size: | 11 kb |
File Type: | docx |
Blackboard Questions
1. Describe what happens in each of the main stages of the cell cycle - G0, G1, S, G2, mitosis, cytokinesis.1. In the G0 phase of the cell, there is a non-dividing state of the cells that are no longer in the cell cycle. Next is the G1 phase, here the first gap is made in the cell cycle. After that S phase occurs. The S phase is DNA replication, the sister chromatids are made. Then G2 phase, the DNA replication and the rest of the cell is being proofread. If the cell is too complicated to fix, the cell performs Apoptosis, which is cell suicide. Then Mitosis occurs, in this phase of the cell, an identical copy of the cell is produced by the end.
In the process of Mitosis, there are 6 different steps. The first one is Interphase, here the cells nuclear envelope encloses the nucleus, 2 centromes have formed by duplication of a single centrosom, and chromosomes are not yet condensed.
Next is Prophase. In prophase the chromatin fibers are more tightly coiled, they are condensed into chromosomes , the nucleoli disappears, chromosomes are duplicated and appear as two sister chromatids, the spindle starts to form, and the centromes move away from each other.
Third is Prometaphase. Here there is no nuclear envelope anymore and the chromosomes become even more condensed than they were before.
Next, metaphase occurs. In this process the centrosomes are at opposite ends of the cell and the chromosomes are at the middle of the cell, usually in a line.
The fifth step of Mitosis is Anaphase. In Anaphase the cell elongates and at the end of this step, the two ends of the cell have an equal amount of daughter chromosomes. Daughter chromosomes is the product of when a sister chromatids separates.
In Telophase, the nuclear envelope starts to reappear, the nucleus appears slightly, and chromosomes become more condensed. At this point the cell is about ready to separate into two identical cells. When the cell separates, it is called cytokinesis.
Information from: Reece, Jane B. Campbell Biology. Ninth ed. Boston: Benjamin Cummings, 2009. Print.
2. During mitosis, why do the sister chromatids separate instead of the homologous chromosomes? Give a complete explanation for this, including the difference between homologous chromosomes and sister chromatids.
During Mitosis sister chromoatids are identical copies of the original chromosome in the cell. Along with the sister chromatids there are homologous chromosomes. These are coded for the same gene but have different alleles. This means that the homologous chromosomes for eyes are both coded to go to the eyes but one could be green and the other for brown eyes. Throughout Mitosis the cell is trying to get an identical copy of its self. To do this the cell must have equal amounts of material in each cell. To get the same amount of DNA into each cell before it separates is to have the sister chromosomes separate in the Anaphase step producing daughter chromatids in each new cell. It does this so that once the cell splits, it will have equal amounts of the same identical DNA. After this, in the G2 phase of mitosis, there is a “proofreading” checkpoint. Here the cell decides if it is correctly separated. If it is not, the cell can try to repair it or if it’s beyond repair, the cell performs Apoptosis, this is cell suicide. If the checkpoint clears the cell, it is perfect and ready to split. The split is called cytotokinesis. After this occurs there will be two identical cells produced.
In the process of Mitosis, there are 6 different steps. The first one is Interphase, here the cells nuclear envelope encloses the nucleus, 2 centromes have formed by duplication of a single centrosom, and chromosomes are not yet condensed.
Next is Prophase. In prophase the chromatin fibers are more tightly coiled, they are condensed into chromosomes , the nucleoli disappears, chromosomes are duplicated and appear as two sister chromatids, the spindle starts to form, and the centromes move away from each other.
Third is Prometaphase. Here there is no nuclear envelope anymore and the chromosomes become even more condensed than they were before.
Next, metaphase occurs. In this process the centrosomes are at opposite ends of the cell and the chromosomes are at the middle of the cell, usually in a line.
The fifth step of Mitosis is Anaphase. In Anaphase the cell elongates and at the end of this step, the two ends of the cell have an equal amount of daughter chromosomes. Daughter chromosomes is the product of when a sister chromatids separates.
In Telophase, the nuclear envelope starts to reappear, the nucleus appears slightly, and chromosomes become more condensed. At this point the cell is about ready to separate into two identical cells. When the cell separates, it is called cytokinesis.
Information from: Reece, Jane B. Campbell Biology. Ninth ed. Boston: Benjamin Cummings, 2009. Print.
2. During mitosis, why do the sister chromatids separate instead of the homologous chromosomes? Give a complete explanation for this, including the difference between homologous chromosomes and sister chromatids.
During Mitosis sister chromoatids are identical copies of the original chromosome in the cell. Along with the sister chromatids there are homologous chromosomes. These are coded for the same gene but have different alleles. This means that the homologous chromosomes for eyes are both coded to go to the eyes but one could be green and the other for brown eyes. Throughout Mitosis the cell is trying to get an identical copy of its self. To do this the cell must have equal amounts of material in each cell. To get the same amount of DNA into each cell before it separates is to have the sister chromosomes separate in the Anaphase step producing daughter chromatids in each new cell. It does this so that once the cell splits, it will have equal amounts of the same identical DNA. After this, in the G2 phase of mitosis, there is a “proofreading” checkpoint. Here the cell decides if it is correctly separated. If it is not, the cell can try to repair it or if it’s beyond repair, the cell performs Apoptosis, this is cell suicide. If the checkpoint clears the cell, it is perfect and ready to split. The split is called cytotokinesis. After this occurs there will be two identical cells produced.