1. Why does the DNA condense into chromosomes during cell division?In order to make it easier to separate into controlled groups.

2. Explain what happens during each of the following phases of the cell cycle in a typical eukaryotic cell:Interphase – the cell grows and duplicates its chromosomes in preparation for cell division, and can be divided into 3 groups G1, S, and G2.a. G1 – G1, or Gap 1, is the first phase of interphase. In this phase, the cell grows and synthesizes mRNA and proteins. b. S – This is the phase in which DNA is replicated.c. G2 – In this phase, the cells prepare to divide.d. Prophase – This is when the chromosomes condense, the nuclear envelope breaks down, and the mitotic spindle begins to form. In animal cells, the centrioles divide.e. Metaphase – Chromosomes are at the metaphase plate, and spindle fibers attach to the kinetochores of the chromosomes (centromeres).f. Anaphase – The chromatids split at the centromeres and the kinetochores pull each sister chromatid to the cell poles.g. Telophase – The chromosomes decondense and the nuclear envelope reforms.h. Cytokinesis – The two daughter cells fully separate.

3. What is different about cytokinesis in animal-like cells as compared to plant-like cells?In animal cells, a cleavage furrow forms from a microfilamental contractile ring and the two daughter cells fully separate. In plant cells, vesicles from both daughter cells help form a new cell wall in the middle.

4. Why does a multicellular organism need to control and coordinate cell division? What might be the consequences of uncontrolled cell division in a multicellular organism?In order to make sure it grows in the right way. The cells could grow uncontrolled and interfere with life processes, i.e. cancer.

5. What does it mean when we say that there are several “checkpoints” that occur during the cell cycle?Checkpoints are proteins that inhibit or don’t inhibit the cell cycle based on factors such as DNA damage and accurate completion of the stage before the checkpoint.

What are the “Questions” that a cell must “answer” during each of the following checkpoints:a. G1/S checkpoint – the moment when the cell can either decide the process of division (DNA duplication) or stop at a resting phase, G0. Some cells, like epithelial cells, enter G0 less thanb. G2 checkpoint – This signals the decision to either start preparation – besides DNA replication – for mitosis, or to just stop due to DNA damage.

c. spindle checkpoint – it doesn’t allow separation of the sister chromatids until they are definitely attached to the spindle fibres, thus regulating the type and amount of chromosomes in each daughter cell.

6. Explain the relationship between cdK, and cyclin.cdK is a kinase that cyclins, a type of protein, attaches to in a cellular signaling pathway. cdK is present in a constant amount, but cyclins are made increasingly through the cell cycle. Their relationship helps regulate and push forward the cell cycle.

7. Compare and contrast the functions of proto-oncogenes and tumor suppressor genes. Give an example of each and explain why mutations in these genes can lead to cancer.Proto-oncogenes accelerate the cell cycle while tumor suppressor genes stop it. Mutated versions of them can get stuck permanently in the ‘on’ or ‘off’ position. For example, if an oncogene is overexpressed, it can cause too much growth, which is cancer.