Correct option is D
Explanation of the correct answer:
DME (DEMETER) is a DNA glycosylase. DME is involved in the active removal of DNA methylation marks, specifically excising methylated cytosines, contributing to DNA demethylation. This process is important for epigenetic reprogramming during seed development.
MEA (MEDEA) is a histone methyl transferase. MEA is a part of the Polycomb Repressive Complex 2 (PRC2) and is involved in the methylation of histone proteins, which results in gene silencing. This action is crucial for the regulation of gene expression during seed development, particularly in the endosperm.
Thus, DME functions as a DNA glycosylase, and MEA acts as a histone methyl transferase, making Option 4 the correct choice.
Information Booster:
DNA Glycosylases: DME, as a DNA glycosylase, helps to excise methylated cytosine from the DNA, playing an essential role in active DNA demethylation, which is required for proper seed development and gene reprogramming.
Histone Methyl Transferases: MEA, as a histone methyl transferase, adds methyl groups to histones, leading to gene silencing. This action is crucial for the regulation of gene expression in the context of endosperm development in Arabidopsis.
Additional Information about Incorrect Options:
Option 1: This is incorrect because MEA is a histone methyl transferase, not a DNA methyl transferase. DME is correctly described as a DNA glycosylase.
Option 2: This is incorrect because DME is not a DNA methyl transferase, but a DNA glycosylase. MEA is indeed a histone methyl transferase, not a DNA methyl transferase.
Option 3: This is incorrect because DME is not a histone methyl transferase, it is a DNA glycosylase, and MEA is a histone methyl transferase, not a DNA methyl transferase.
