Epigenetics in Human Health and
Disease Questions and answers
What is an epigenetic modification? - ✅✅A modification that mediates changes in gene expression in
the absence of change to the underlying DNA sequence.
What is:
Chromatin?
Nucleosome?
Histone?
Histone tail?
Post-translational Modifications (PTMs)? - ✅✅Chromatin is a mixture of DNA and proteins that form
the chromosomes.
Nucleosomes are the basic packing units of genomic DNA built from histone proteins around which DNA
is coiled.
Histone is a protein that provides structural support for a chromosome.
Histone tails are flexible regions that protrude from the nucleosome core.
Post-translational Modifications (PTMs): covalent modification of specific amino acids in the histone tail.
What are the types of PTMs? - ✅✅Methylation, physphorylation, acetylation etc.
What is the histone code? - ✅✅Posttranslational modifications with functional consequences; can be
written, reased and read by specific proteins.
What is euchromatin and heterochromatin? - ✅✅Euchromatin represents genes that can be
transcribed because the DNA is open. Heterochromatin contains the inactive genes, inactive because
they are closed.
What is DNA methylation? - ✅✅This is a covalent modification and occurs primarily at the CpG sites
in vertebrates. This can switch genes on and off at gene promotors and can dim the gene at gene
enhancers. It is the addition of a methyl group to DNA at the CpG site. It usually results in blocked
transcription.
What is the 'life cycle' of DNA methylation? - ✅✅Methylation can be maintained while cells divide
but it requires DNMT1 (maintenance DNA methyltransferase).
De novo DNA methylation is the methylation of regions that were previously not methylated and
requires DNMT3A/B.
Disease Questions and answers
What is an epigenetic modification? - ✅✅A modification that mediates changes in gene expression in
the absence of change to the underlying DNA sequence.
What is:
Chromatin?
Nucleosome?
Histone?
Histone tail?
Post-translational Modifications (PTMs)? - ✅✅Chromatin is a mixture of DNA and proteins that form
the chromosomes.
Nucleosomes are the basic packing units of genomic DNA built from histone proteins around which DNA
is coiled.
Histone is a protein that provides structural support for a chromosome.
Histone tails are flexible regions that protrude from the nucleosome core.
Post-translational Modifications (PTMs): covalent modification of specific amino acids in the histone tail.
What are the types of PTMs? - ✅✅Methylation, physphorylation, acetylation etc.
What is the histone code? - ✅✅Posttranslational modifications with functional consequences; can be
written, reased and read by specific proteins.
What is euchromatin and heterochromatin? - ✅✅Euchromatin represents genes that can be
transcribed because the DNA is open. Heterochromatin contains the inactive genes, inactive because
they are closed.
What is DNA methylation? - ✅✅This is a covalent modification and occurs primarily at the CpG sites
in vertebrates. This can switch genes on and off at gene promotors and can dim the gene at gene
enhancers. It is the addition of a methyl group to DNA at the CpG site. It usually results in blocked
transcription.
What is the 'life cycle' of DNA methylation? - ✅✅Methylation can be maintained while cells divide
but it requires DNMT1 (maintenance DNA methyltransferase).
De novo DNA methylation is the methylation of regions that were previously not methylated and
requires DNMT3A/B.
