This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
All are true regarding epigenetics mechanism except: 
Select and explain. 
A. Non-heritable, B. Acetylation of Histone, C. Hereditary, D. Methylation of DNA
A: Non-heritable
Answer: A: Non-heritable 
Explanation: Ans. (A) Non-heritableEpigenetics is defined as the study of heritable chemical modification of DNA or chromatin that does not alter the DNA sequence itself. Example of such modification include methylation of DNA & the methylation er acetylation of histones.Epigenetic modification is critical for normal development including-regulation of tissue specific gene expression, X-chromosome inactivation & genomic imprinting.An epigenetic modification refers to a change in the genome, heritable by cell progeny, that does not involve a change in the DNA sequence. The inactivation of the second X chromosome in female cells is an example of an epigenetic silencing that prevents gene expression from the inactivated chromosome.