Final answer:
Examples of proto-oncogenes and tumor suppressor genes include Cdk, as well as RB1, p53, and p21, which play crucial roles in regulating the cell cycle and preventing uncontrolled cell division. Alterations in these genes can disrupt the balance of cellular 'acceleration' and 'braking,' promoting the development of cancer.
Step-by-step explanation:
Certain genes discussed in Module 4 that can be categorized as proto-oncogenes or tumor suppressor genes include the following:
Proto-oncogenes: These are normal genes which, when mutated or expressed at excessively high levels, can promote cell division and contribute to cancer. An example is the Cdk gene, which can lead to increased cell cycle progression when altered. Other examples include genes encoding for cell-surface receptors for growth factors or cell-signaling molecules.
Tumor suppressor genes: These encode for proteins that prevent uncontrolled cell division. Notable tumor suppressor genes include retinoblastoma protein (RB1), p53, and p21, which act as critical checkpoints, preventing the cell from undergoing division if there are DNA problems or until certain cellular events have been completed.
The process of a cell becoming cancerous involves changes in these genes, leading to an imbalance between the 'accelerate' and 'brake' functions of the cell's regulatory mechanisms. Cancer may result from an overactive proto-oncogene (the accelerator) or an underactive tumor suppressor gene (the brake).