Eukaryotic Gene regulation: Events
What happens
Pre-Transcription
Chromatin remodeling
Acetylation unwinds DNA from histones,
making genes accessible to transcribe.
HAT- Histone acetyltransferase enzyme
adds acetyl groups to offset some of the
positive histone charge, decreasing
DNA’s affinity for the histones.
HDAC-removes acetyl groups once a
specific region of DNA is accessible.
CRC-Chromatin remodeling complex
uses ATP to move the histone away from
the DNA.
Methylation winds DNA around histones
tighter, preventing gene transcription.
Regulatory TFs are proteins that regulate
transcription, are produced specific to
cell’s environmental signals, help turn
on/off genes, can be *activators &
enhancers* help RNA Polymerase form
an active transcription initiation complex
on the promoter region.
Post-Transcription
Modify pre-mRNA: inc mRNA stability,
facilitates transport into cytoplasm,
protects coding regions from degradation,
allows the two ends of mRNA to
associate with each other and helps find
the ribosome to initiate translation.
5’ Guanine cap
3’ poly-a tail - inc. length inc. rounds
available for translation. The enzymatic
shortening of poly-a-tail helps trigger
removal of 5’ cap, endonucleases ready
to chew up the mRNA.
Alternative splicing of exons by different
spliceosomes in different cells leads to
different protein expression across
different cell types. This amplifies the
number of proteins that can be produced
from a set number of genes.
