Lecture 20: Control and Regulation of Gene Expression
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Differentiated cells can be de-differentiated to become ______ again
Pluripotent
What type of cell contains the genetic instructions necessary to direct the formation of a complete organism?
Differentiated cells
Why do cell types differ?
Because they express different genes and make different sets of proteins
Prokaryotes and eukaryotes exhibit many differences in?
Genome organization and expression
What are three types of gene regulation that exist in eukaryotes?
Environmental regulation Tissue-cell type specific regulation Developmental regulation
What do organisms have to control for every single protein that’s produced in a specific cell type?
Developmental time, amount, and localization of every single protein must be controlled
The multiple steps of regulations that cells undergo are catalyzed by?
enzymes
What are the five major levels of gene expression regulation?
Genome, transcriptional, post-transcriptional, translational, and post-translational regulation
What is the central question of genome regulation?
Which genes are available for transcription?
What molecular structure plays a key role in genome accessibility?
Chromatin/histones and their modifications
What is the main question addressed by transcriptional regulation?
When and how is an available gene transcribed?
Which transcriptional stages can be regulated?
Initiation, elongation, and termination
Name three mRNA processing events regulated after transcription
Capping, splicing, and poly-A tailing
What determines which mRNAs are transported from the nucleus to the cytosol?
Selective mRNA export mechanisms
What affects how long an mRNA lasts in the cell?
The rate of mRNA degradation
What are the main questions in translational regulation?
Which mRNAs are translated, and how efficient is translation?
Where does translation occur?
In the cytoplasm on ribosomes/polysomes
What types of mods can occur to proteins after translation?
Modifications that affect folding, activity, or localization (such as phosphorylation, glycosylation)
What regulates how long a protein remains in the cell?
Protein degradation pathways
Why are post-translational mods important?
They determine protein activity, function, and cellular localization
At what level does gene expression regulation in prokaryotes primarily occur at?
Primarily occurs at the transcriptional level in prokaryotes
What operon example is illustrated on slide 6?
The tryptophan (trp) operon (this is a regulatory system)
What acts as the allosteric effector in the trp operon system?
The end product, tryptophan (trp)
What is an allosteric effector?
a molecule that binds to a protein at a site other than the active site, changing the protein’s shape and, in turn, its activity