Lecture 16
Regulation of Gene Expression
Gene expression: the
process by which a gene’s
DNA sequence is converted
into a gene product – protein (mRNA),
tRNA, or rRNA
Each step in the process
of gene expression can
be regulated
DNA is packed
into chromatin
Step1: Modifying the
chromatin
structure:
histone acetylation or
methylation
Step 2: Regulation of Transcription
Promoter/Enhancer function
depends on available
transcription factors:
different cells have different
transcription factors
available
Step 3: Post-transcriptional Regulation
Step 4: Regulating mRNA stability and Step 5:
Regulating Initiation of Translation
Step 6: Regulating Protein Stability
Genetic changes that make things go awry…..
proto-oncogene: a normal gene
that can become an oncogene
oncogene: a modified gene
that encodes for a protein that
can increase the chance that a
normal cell can become a tumor cell
or convert a tumor cell to a malignant cell
ras: GTP-binding protein
-part of the MAPK
pathway (signal
transduction)
-this pathway induces cell
division
p53: DNA binding protein
-holds a cell
at the G1/S or G2/M
boundary
-induces DNA repair
machinery