How do normal cells protect themselves from accumulating mutations in genes that could lead to cancer? How do cancer cells differ from normal cells in these processes?

Verified step by step guidance

1. Understand that normal cells have multiple mechanisms to protect their genome integrity and prevent the accumulation of mutations. These include DNA repair systems, cell cycle checkpoints, and programmed cell death (apoptosis).
2. Recognize that DNA repair mechanisms detect and correct errors that occur during DNA replication or due to environmental damage. Examples include mismatch repair, nucleotide excision repair, and double-strand break repair.
3. Learn that cell cycle checkpoints act as surveillance points where the cell assesses DNA integrity before proceeding with division. If damage is detected, the cell can pause the cycle to allow repair or trigger apoptosis if the damage is irreparable.
4. Know that apoptosis is a controlled process by which cells with severe DNA damage self-destruct, preventing the propagation of mutations that could lead to cancer.
5. Contrast this with cancer cells, which often have defects in these protective mechanisms—such as mutations in tumor suppressor genes like TP53—leading to impaired DNA repair, faulty checkpoints, and resistance to apoptosis, allowing them to accumulate mutations and proliferate uncontrollably.

Key Concepts

DNA Repair Mechanisms

Normal cells have multiple DNA repair systems that detect and fix mutations caused by environmental damage or replication errors. These mechanisms, such as nucleotide excision repair and mismatch repair, maintain genetic stability and prevent mutation accumulation that could lead to cancer.

Cell Cycle Checkpoints

Cell cycle checkpoints are control points where cells assess DNA integrity before progressing through division. In normal cells, these checkpoints halt the cycle to allow repair or trigger apoptosis if damage is irreparable, preventing propagation of mutations.

Differences in Cancer Cells

Cancer cells often have defective DNA repair and checkpoint pathways, allowing mutations to accumulate unchecked. They may evade apoptosis and continue dividing despite genetic damage, leading to uncontrolled growth and tumor development.