MARIA - LECTURE 2 Flashcards
generating mRNA for translation in bacteria vs eukaryotes
what are the three parts of pre-mRNA processing in eukaryotes
what are the advantages of translational control
what proportion of the cell’s energy and genes go towards protein synthesis
what is the anatomy of prokaryotic mRNA
what is the anatomy of eukaryotic mRNA
anatomy of mitochondrial mRNAs
there are only 13 of them
what do eukaryotic mRNAs start with at their 5’ end?
start with a 5’ triphosphate group
what is the structure of the 7-methylguanosine cap
all mRNAs have this, absolutely no exceptions
what is the mRNA capping reaction
when is the cap added to mRNA
added co-transcriptionally, after the synthesis of about 25 bases
what are capping enzymes bound to
what does the cap give to the mRNA
splicing and polyadenylation are stimulated by the presence of the cap
required for nuclear export
confers stability, protects from cleavage
required for translation
how do DNA viruses deal with the need to cap their mRNA templates?
how do cytoplasmic RNA viruses deal with the need to cap their mRNA templates
don’t have access to RNA polymerase II, they have evolved their own capping machinery
how do viruses that do not encode caping enzymes deal with the need to cap their mRNA
can steal it from the host (Cap Snatch)
how does the cap snatch mechanism work
the cap snatch mechanism can be a drug target, such as baloxavir
what does the 5’ end of the picornaviruses look like
how does picornavirus use VPg as an alternative to the cap
which protein recognises foreign CAPs as an antiviral innate immune response
IFIT1: interferon-induced proteins with tetratricopeptide repeats
how do non self caps perfectly fit into the IFIT1 protein
what is the polyadenylation signal
10-30 nucleotides of an AU rich sequence
CA
and after than GU-rich ur U rich
how is the poly A tail added
what is a notable exception of an RNA pol II transcript that does not undergo polyadenylation
histone mRNAs don’t have poly A tails
what is the poly A tail involved in
involved in mRNA stabilization and export from the nucleus
also stimulates translation initation
structure of a tRNA
how are translation extracts prepared
how did we figure out how many nucleotides per codon
then he did it with UCUCUCUCU
how did we figure out the different combinations of trinucleotides and amino acids
characteristics of tRNAs
first ever biologically active nucleic acid sequenced
how come the same tRNA can decode more than one codon
Wobble pairing done by the first nucleotide
what are the binding pairs of the wobble hypothesis
G -> C/U
U -> A/G
I -> A/C/U
how are amino acids linked to tRNAs
