Molecular Biology Of The Cell 6th Edition by Bruce Alberts, Alexander Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter Walter

Exercise 9

With age, somatic cells are thought to accumulate genomic "scars" as a result of the inaccurate repair of dou- ble-strand breaks by nonhomologous end joining (NHEJ). Estimates based on the frequency of breaks in primary human fibroblasts suggest that by age 70, each human somatic cell may carry some 2000 NHEJ-induced muta- tions due to inaccurate repair. If these mutations were distributed randomly around the genome, how many pro- tein-coding genes would you expect to be affected? Would you expect cell function to be compromised? Why or why not? (Assume that 2% of the genome-1.5% protein-cod- ing and 0.5% regulatory-is crucial information.)