Question

Cancer can be caused by

		increased expression of proto-oncogenes
		second hand smoking
		reduced methylation of proto-oncogenes
		all provided answers are correct
		by abnormal levels of methylation in the genome
		reduction in the expression of a suppressors gene

Answer 1

Answer- all provided answers are correct

Explanation-

1.Oncogenes arise due to mutations that increase the expression level or activity of a proto-oncogene.

2.Secondhand smoke causes lung cancer in adults who have never smoked by 20- 30%

3.Studies show that due to decreased methylation, relief of transcriptional silencing, may allow the expression of previously quiescent protooncogenes to become active and induce the cell proliferation events.

4. Usually a suppressor gene can also be inactivated by a process called DNA methylation, which involves an enzyme called DNA methylase adding methyl groups to sites at or near the gene and this process is said to be epigenetic because the sequence of bases in the DNA is not changed.

Hope this helps you. Thank you ?