Fundamentals of Molecular Biology - V.I. Rezyapkin 2009

DNA Repair
SOS Response

SOS repair is utilized when DNA damage becomes so extensive that The Cell faces imminent death. The degree of induction for this type of repair is directly proportional to The amount of DNA damage. With a low level of damage, the number of repair Proteins increases; with greater damage, Cell Division is temporarily halted and the synthesis of an even larger number of repair proteins is induced. When damage reaches critical levels, the cell synthesizes proteins that enable DNA polymerase to synthesize the daughter DNA strand by using defective segments of the template strand (Fig. 3.10). Consequently, numerous errors are introduced into the newly synthesized DNA strand. Thanks to SOS repair, METABOLISM/36.html">DNA Replication proceeds, allowing the cell to divide. The daughter Cells will survive if the vital Functions encoded in the DNA remain intact; otherwise, they will perish.

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Fig. 3.10. The Role of DNA polymerase in SOS repair

Summarizing the above, it should be noted that living systems possess numerous repair mechanisms that ensure the stability of genetic material across generations. Malfunctions in these systems can lead to catastrophic consequences, resulting in various Genetic Disorders (such as xeroderma pigmentosum, Cancer, etc.) and even organismal death.