Regulation of gene expression Flashcards
Amount of protein is determined by the rate of (3)
transcription
translation
degradation of mRNA or protein
activity of a protein is determined by (2)
protein cleavage
protein modifications
A common way for cells to regulate gene expression
controll transcriptioin
transcription of a gene is off/low
absence of activator or presence of repressor
transcription is on/high
presence of activator/lack of repressor
transcription in prokaryotes
organize related genes into operons
transcription in eukaryotes
have shared regulatory sequences
operon
functionally related genes
what do operons produce
multiple proteins from a single mRNA transcript
inducible operon
turned off until the products of gene expression are needed
repressible operon
turned on until the products of gene expression aren’t needed
An famous example of an inducible operon
lac operon
When is the lac operon repressed
when lactose is absent
What type of operon is the trp operon
repressible
when is the trp repressor active
when tryptophan is bound
The gal operon is an inducible that contains genes necessayr for galactose metabolism What is not true about the gal operon
galactose binds to the operator
How are eukaryotic cells transcription regulated?
by proteins that bind to enhancers located in and around genes
what are enhancers
DNA sequences in the regulatory regiion of a gene that can increase transcription from a nearby promoter
Enhancer-bindiing proteins promote what
transcription
Location of enhancers
may be distant from the promoter
mediator proteins
makes all the factors come together
more transcription factors effect on producing gene
more gene produced
Cell differentiation
process by which cells become specialized
selective expression of different genes
can give rise to different cell types
situ hybridization
used to detect the presence and location of mRNA from one specific gene
microarrays allow for what
global analysis of gene expression
Single cell RNA-seq
can be used to characterize the transcriptome of complex tissues
RNA sequence reveals
gene expression varies even in seemingly homogenous tissues
Two histone modifications
acetylation and methylation
acetylation
transcriptional activation
methylation
transcriptional repression
DNA modification
cytosine methylation
cytosine methylation
transcriptional repression
nucleosome
packaging DNA unit
methylation of cytosines in
CpG islands represses transcription
epigenetic modifications
change chromatin structure
Environmental factors
affect DNA methylation and have effects on health
Alternative splicing
a form of differential gene expression
microRNAs
regulate eukaryotic gene expression by blocking translation or promoting mRNA degradatioin
three facts about miRNA
- tissue and developmental stage specifific miRNA exprfession
2.more than 60% of genes regualted by miRNA - each miRNA can regulate multiple mRNA targets
microRNAs in plants
regulate gene expression
Long non-coding RNAs (lncRNA)
regulate gene expression such as guiding, scaffolding
postranslational mechanisms for regulating gene expression (5)
- reversible modifications like phosphorylation
- regulation of protein folding (chaperones)
- interactions with small molecules like Ca2+
- proteolytic cleavage
- ubiquitin-mediated protein degradation
