Candidates should be able to relate their understanding of the cell cycle to cancer and its treatment.

If there is a change in the DNA that controls the cell cycle, there can be an increase in the speed that cells grow at.

One cell with this mutation will rapidly divide into to, and this will continue to create a large group of cells, called a tumour.

These tumours are potentially disruptive to the functions of organs, as we know cancer takes many lives.

Chemotherapy is the use of chemicals to inhibit the cell cycle. They effect parts of the cell cycle for example: stopping spindle formation in the metaphase; stopping DNA replication during synthesis.

These chemicals effect the cycles of all cells in the body, but they will have a bigger effect the faster the cycle. This means that cancer cells are significantly slowed, but so are other quickly replicating cells are too, like hair cells.

Mitosis and the cell cycle. DNA is replicated and this takes place during interphase.

After a cell is created it goes through a several stages:

1. G1: the first phase of growing, when proteins and organelles are being made
2. S: synthesis, when DNA is being replicated
3. G2: the second phase of growth when organelles and energy supplies are increased
4. Prophase: chromosomes become visible, nuclear envelope and nucleolus disintegrate
5. Metaphase: chromosomes line up in the middle of the cell; spindle fibres form
6. Anaphase: Spindle fibres contract pulling chromosomes to the poles
7. Telophase: nuclear envelopes and nucleoli form around both sets of DNA
8. Cytokinesis: the cells cytoplasm divides into two

1, 2, and 3 are all part of the 'interphase' when the cell is not in the process of replicating.

4, 5, 6 and 7 are all part of mitosis, which is explained in greater detail in the following post:

This diagram represents the cell cycle:

(ignore the check point markings)

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