Epigenetics (14.3) Flashcards
(14 cards)
Epigenetics
Heritable changes in gene expression that do not change the DNA sequence
Inheritance of epigenetic modifications can be
Somatic, transgenerational, programmed, environmental
Chromatin remodeling and gene accessibility is regulated through epigenetic modifications including:
DNA methylation, histone modifications and ncRNAs
What does DNA methylation do?
condense chromatin strucutres leading
What does histone tail acetylation tend to do?
Relax chromatin structure leading to high gene expression
CpG dinucleotides
Targets for methylation
5’-cytosine-phosphate-guanine-3’
5’-GpC-3’ vs 5’-CpG-3’
Cpgs are more clustered in beginning of the gene while GpC are more evenly distributed
CpG islands
Clusters of CpG sequences
Where are CpG islands located frequently?
promoter regions
DNA methylation at CpG Islands tends to inhibit transcription. How?
Sometimes through inhibition. Methylation can prevent activators, transcription factors or RNA polymerase from binding to DNA
Sometimes thorugh recruitment
DNA methylation can recruit proteins that condense chromatin
Do all promoters have CpG islands?
No
Are all CpG sites methylated?
No
How are DNA methylation patterns inherited?
Methylated DNA acts as a template for methyl transferases (enzymes that add methyl groups)
After DNA replication in interphase, methylated DNA on the “old” strand can recruit DNA methylases that add methyl groups to newly synthesized strand
X-Inactivation
Epigenetic process because daughter cells remember which X-chromosome is condensed into barr bodies
