Practice question

Somatic mutations occur after fertilization in embryonic or adult somatic lineages derived from mitotic divisions of zygote, affecting tissues such as skin, blood, or epithelium but not entering germline due to sequestration of primordial germ cells early in development. According to Weismann doctrine, somatic genome modifications are not transmitted through gametes to offspring, though they can cause mosaicism, clonal expansion, or neoplasia within individual. Consequently somatic events influence cancer risk and aging but not population allele frequencies or inherited disease transmission. This principle illustrates essential molecular mechanisms governing replication fidelity and mutation fixation relevant for exam interpretation.