Question

Explain epigenetics by discussing specific molecular modifications and enzymes. Does epigrnetics support the work of Jean-Baptiste Lamarack? Why or why not?

Answer 1

Epigenetics is the study of phenotypic traits which can be inherited without undergoing any change or alterations within the sequence of DNA. With such phenotypic traits, it might undergo a change in the gene activity and expression and inherits the phenotypic traits which might occur due to certain environmental change. When the genome is affected by the environmental factors, it undergoes some sort of molecular modifications and hence helps in causing differentiation within the higher organisms. Some of the examples of the same are histone modification or DNA methylation which can change the pattern in which the genes can be expressed.

With help of epigenetic modifications, there are some chemical tags which are able to alter or adjust the gene expression without making an change within the DNA sequence. In case of DNA methylation, a methyl group is added to the DNA molecule which can change the expression of the gene sequence but it does not cause any sort of alteration or change in the DNA sequence. This process is important as it helps in many processes like genomic imprinting, inactivation of X-chromosome, aging etc. In mammals, the DNA methylation is important after very DNA replication cycle and it is aided with help of the DNA methyltransferase enzyme. When the enzyme is not present, it would produce daughter strands which are unmethylated and gradually would cause cells with passive demethylation. Another example for the same is histone modification and this protein in tightly wrapping the DNA. When the histone protein is absent, the chromatin will be not wrapped properly and will be long which would not allow it to be accommodated within the nucleus. The histone modification is a type of modification like methylation, acetylation, phosphorylation etc. and such modification can impact the gene expression without changing the DNA sequence and does so by altering the chromatin structure.

Yes, epigenetics somewhat support the work of Lamarck as according to Lamarck it was mentioned that organism and living forms tends to acquire and gain their traits based on their environment and hence it is passed on. According to epigenetics, it is the passage of the phenotypic traits from one generation to another and traits can be changed based on the environmental factors and alters the DNA expression but it does not change the DNA sequence. Hence since epigenetic state that gene expression can be changed due to some environmental or external factors over time and inherited, it somewhat supports the Lamarck’s theory.