Final answer:
Mutations in genes responsible for mismatch repair are estimated to cause up to 15% of colon cancers. These genetic alterations disrupt the DNA repair process, leading to unchecked cell division and tumor formation. Specifically, the p53 gene is a well-known example of a repair gene whose mutation is associated with various cancers.
Step-by-step explanation:
The factor estimated to be responsible for up to 15% of colon cancers is mutations in genes that encode the proteins required for mismatch repair. These mutations affect the cell's ability to correct errors that occur during DNA replication. If these errors are not corrected, it can lead to uncontrolled cell division and cancer. Genetic mutations in repair genes like the ones responsible for mismatch repair mechanisms have been implicated in various forms of cancer, including pancreatic, colon, and colorectal cancer. Therefore, the correct answer to the student's question is (b) mutations in genes that encode the proteins required for mismatch repair.
Common mutations include changes to genes such as p53, which is responsible for detecting and repairing damaged DNA, thus acting as a tumor suppressor. When genes such as p53 become mutated, they may produce proteins that are unable to carry out their role in DNA repair correctly, leading to the development of cancer. Mutations in these repair genes might be the result of errors during DNA replication or exposure to carcinogens, including various chemicals and radiations.