Cell Divison

Question	Answer
Genetic Control of cell division	1. Cell division is controlled by genes. Most cells divide to ensure cells are replaced.
In normal cells, two types of genes control cell division.	1. Proto-oncogenes stimulate cell division 2. Tumour suppressor gene slow cell division
Role of Proto-oncogenes-01	In a normal cell, growth factors attach to a receptor protein on the cell surface membrane and, via relay proteins in the cytoplasm.
Examples of growth factors	1. Proteins 2. Hormones
Role of proto-oncogenes -02	Gene mutation can cause proto-oncogene to mutate into oncogenes. 1. Receptor protein on the cell-surface membrane can be permanently activated, so the cell division is activated even in the absence of growth factors. 2. The oncogene may code for a growth factor, that is then produced in excessive amounts, and stimulate excessive cell division.
Role of tumour suppressor genes	1. In normals cells, this gene maintain normal rates of division and prevent the formation of tumours. 2. If a tumour suppressor gene is mutated it is inactivated so it stops inhibiting cell division, which therefore increases.

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	Created by prettypriyaz over 10 years ago