Epigenetics Flashcards
epigenetics
the study of influences on gene expression that occur without a DNA change
epigenetic tags
methylation of DNA or acetylation of histone proteins
what do methyl groups attached to DNA do?
silence genes by adding a methyl group to cytosine by methyltransferase
what do histone proteins do?
they become more or less tightly bound to DNA so that it is more or less accessible (the less tightly bound, the increased chance of gene expression)
demethylase
catalyzes removal of methyl groups
methyltransferase
enzyme that methylates newly synthesized DNA strands and are involved in mismatched repair; can be used to silence genes that promote uncontrolled cell growth (e.g. cancer)
what process does methylation affect?
transcription (occurs on the DNA)
what do acetyl groups do?
promote gene expression by minimizing the negative charge of DNA; this occurs on histone proteins
what separates epigenetic changes from mutation?
epigenetic changes are inherently reversible, while mutations tend to be irreversible
gene expression
the process by which information encoded in a gene is converted to a protein product that determines an organism’s characteristics and functioning
what happens at the molecular level of genetics?
epigenetics refers to the addition or deletion o a methyl group to a DNA base, turning the gene on or off, or to packaging of the chromatin structure by silencing/opening regions of the genome by winding/unwinding the DNA around histones
what factors may cause epigenetic changes?
environmental interactions i.e. smoking, eating, drinking, exercise, exposure to natural and manufactured chemicals in air, water, and food
chromatin remodeling
modification of chromatin architecture to allow access of condensed genomic DNA to the regulatory transcription machinery proteins, and thereby control gene expression
histone acetyltransferase (HAT)
an enzyme that loosens the compaction of chromatin by attaching acetyl groups to histone proteins (minimizes -ve charge of DNA by adding acetyl group to lysine)
histone deacetylases (HDACs)
condense chromatin by removing acetyl groups from histone proteins (re-packages DNA)
