Flashcards in 20.4 epigenetic control of gene expression Deck (16):
process by which environmental factors can cause heritable changes in gene function without changing the base sequence of DNA
chemical tags that determine the shape of the chromatin
which bit of the contents of the nucleolus is fixed?
which bit of the contents of the nucleolus is flexible
what do the epigenetic tags respond to?
signals in the environment e.g. diet, stress and toxins
how does the epigenome adjust the chromatin?
- makes some chromatin tightly wrapped so are inaccessible to transcriptional factors
- makes some chromatin loosely packed so are easily accessible to transcriptional factors
what are the 2 ways in which signals from the environment can caused condensation of the chromatin?
- decreased acetylation of histones
- increased methylation of DNA
how does decreased acetylation of histones cause the gene to become inaccessible?
- increases the positive charges on the histones
- increases the attraction to the phosphate group on the DNA
- gene switched off
what are the 2 ways in which increased methylation inhibits transcription of genes?
- preventing the binding of transcriptional factors to the DNA
- induced deacetylation, making the DNA inaccessible to transcriptional factors
process where an acetyl group is transferred to a molecule
process where an acetyl group is transferred from a molecule
process where a methyl group is transferred to a molecule
process where a methyl group is transferred from a molecule
what is the increased methylation of DNA?
methyl group is added to the cytosine bases of DNA
what are 2 ways in which cancer can be caused?
- activation of a normally inactive gene
- inactivation of a normally active gene