Lecture 7 Flashcards
What can mRNA localization be used for?
Regulating gene expr4ession
3 stages of translation
Initiation, Elongation, Termination
How does trnalation take place more specific
Small subunit binds to RNA and is joined by the large subunit and aminoacyl tRNA binds
Ribosome moves along and extends by transferring peptidyl tRNA to aminoacyl tRNA
Polypeptide is released
What is the Pre-initiation complex?
initiation factores and small subunit
Where does iron uptake take place?
In the intestine
Which factors play a major role in iron hoeostasis
Ferritin and Transferrin receptor
What does the iron regulatory protein do?
If the IRP is open it allows mRNA translation if it is closed it blocks translation and mRNA is degraded
What is the structure of the exosome?
ribonucleolytic complex, catalytically inactive, substrates enter through a pore, enter 3to 5, involved in RNA quality control in the nucleus
What are microRNAs (miRNAs)
either encoded as individual genes (monocystronic) as gene
clusters (polycistronic) or in introns of host genes (intronic).
Synthesized by RNA Poly II
What do miRNAs do?
Silence gene expression by inhibiting translation at the initiation step and initiate mRNA decay (by deadenylation)
Whats is special about the quantity of miRNAs involved in regulation of mRNA?
one miRNA can target many different mRNAs, and one mRNA can be regulated by many different miRNAs
What decay mechanisms exist?
Nonsense mediated decay (premature stop codon decay)
Nonstop decay (mRNA lacking in frame termination codon)
No-Go decay (stalled ribosome)
What degradation pathways of mRNA exist in eukaryotes
deadenylation-dependet decay
Deadenylation-independent decay
Endonucleolytic decay
