Genomic imprinting is a mechanism by which gene expression is regulated. Which of the following correctly defines this mechanism?
A) activation of expression by hypermethylation of genomic DNA sites
B) activation of expression by hypomethylation of genomic DNA sites
C) expansion of trinucleotide repeats in imprinted genes resulting in regulated expression
D) inhibition of expression by hypomethylation of genomic DNA sites
E) regulated expression dependent upon parental origin of regulated gene

Question

Quizplus · Accepted Answer

Genomic imprinting is a genetic phenomenon where certain genes are expressed in a parent-of-origin-specific manner. This means that the expression of the gene depends on whether it is inherited from the mother or the father.  Genomic imprinting refers to a genetic phenomenon, whereby there is preferential expression of a gene from only 1 of the 2 parental alleles. This phenomenon of allele-specific expression results from allele-specific epigenetic modifications such as CpG dinucleotide methylation or histone methylation or histone acetylation. These modifications are referred to as epigenetic modifications (also referred to as epigenetic "marks"). In nonimprinted regions of the chromosomes, the parental epigenetic marks are erased in the germ cells only to be newly established in a parental-specific manner. Once the parental-specific epigenetic marks are established, they are maintained following fertilization.

Genomic Imprinting Is a Mechanism by Which Gene Expression Is