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1. Mitosis is specifically focused on division of the nucleus, or more specifically, the proper division of the replicated chromosomes. Cytokinesis occurs after mitosis and is when the entire cytoplasmic contents of the cell is split in half.
2. Fill in the blanks: After the S phase, each chromosome is now composed of two genetically identical sister chromatids and they are attached at the centromere.
3. There are three checkpoints that a dividing cell must pass through: the G1 checkpoint, the G2 checkpoint, and the M checkpoint (during mitosis).
4. The cell is currently in the G2 phase of the cell cycle. Each of the chromosomes have already been replicated in the S phase (as indicated by the presence of two sister chromatids attached to one another), and there are two centrosomes (organelles are copied during G2).
5. Absolutely. There are many instances when a cell should NOT divide and instead will exit the cell cycle during the G1 checkpoint. A cell will then be in the G0 phase, and instead of actively dividing, will instead just do its cellular thing (whatever that may be).
6. During G1, the cell grows in size and performs normal metabolic functions for the given cell type. During S, DNA will be replicated (synthesized) in preparation for cell division. In G2, the cell will copy its organelles to ensure the two daughter cells have the correct assortment. Finally, the cell divides into two, first by mitosis (division of the chromosomes), and then cytokinesis (division of all the cytoplasm).
7. Any genetic differences between daughter cells after mitosis are considered to be mutations. False! The goal of mitosis is to create two genetically identical daughter cells.
8. If a cell fails a checkpoint but has already copied its DNA, it may undergo apoptosis in order to prevent a defective cell from dividing (and possibly becoming cancerous).
9. The cell is currently in metaphase. The middle dividing line (the metaphase plate) has one sister chromatid on either side. This ensures when the cell splits in two, each resulting daughter cell will receive one copy of each chromosome.
10. Growth factor
11. b. Apoptosis occurs when a cell is not functioning properly. Instead of dividing, the cell will destroy itself.