DNA Transcription I Flashcards
Sigma factor
Component of bacterial RNA polymerase that detaches from polymerase when polymerase reaches the start site of transcription and re-binds to polymerase after polymerase reaches the stop site
What is sigma factor replaced with in eukaryotes?
general transcription factors
What are the factors that affect the rate of synthesis of proteins?
GTFs
Activators
Repressors
Amount of chromatin available for protein synthesis/transcription
What is the role of RNA polymerase?
To synthesize all classes of RNA (mRNA, rRNA, tRNA, sNRPs)
Roles of the different classes of RNA?
mRNA - code for proteins
rRNA - synthesize proteins
tRNA - adapt mRNA to amino acids
sNRP - excise pre-mRNA & transport protein to ER et alii
What do -35, -10, +1 mean?
They are indicators along the DNA strand of when transcription should begin. +1 is the location of the start site. Think of it as a countdown.
How do genes fit into transcription?
Genes are the ones being transcribed. That is to say, not all DNA is transcribed into RNA within a cell.
What is the name of the strand that is being used to code? What else are needed with it?
Template strand. Ribonucleoside triphosphates
What does rifampin do?
Blocks initiation of transcription of TB organism
What are unique factors of prokaryotic RNA?
No nucleus
Transcription & translation occur simultaneously (no modifications before-hand)
One polymerase for all proteins
Shorter half-life (2-10 min vs euk 2-24 hrs)
How do prokaryotic & eukaryotic genes differ?
Eukaryotic have introns & exons
What is an exon?
The piece of the gene that will be coded into RNA
Identify the polymerases to their eventual RNA classes
RNA polymerase I - rRNA
RNA polymerase II - mRNA
RNA polymerase III - tRNA
What is unique about an enzyme associated with RNA polymerase II?
It is modified along the way by RNA capping, polyandeylation, methylation. This doesn’t happen with tRNA or rRNA
What is a key factor in gene regulation in bacteria?
Environment
What about activators? (bacteria)
Activators assist in the transcription of bacterial RNA
Describe trp and lac repressors (bacteria)
Tryptophan repressor binds to a ligand that inactivates the gene for transcription
Lac operon is a repressor unless lactose is available
Why are we so concerned with bacterial RNA transcription?
Because antibiotics can act against bacterial RNA synthesis
What is common for gene regulatory proteins?
The fact that they exist in bacteria and humans and work similarly
What is a transactivation domain?
Domain where proteins bind to other proteins to allow transcription to occur
What is a DNA binding domain?
Region that recognizes and binds to DNA with a gene of interest. These can have several different repeat motifs
What is a ligand binding domain?
Region that regulates activity of gene protein by changing the conformation of gene regulatory protein
What is unique about regulatory proteins?
Can sense sequence of double-stranded by making protein-to-DNA H-bonds specific to certain DNA
What is different about eukaryotic cell growth?
Gene regulation is driven by cell differentiation and growth
