L01-5
Why does Chargaff's rule not hold true for RNA?
Because Chargaff's rule describes that G=C and A=T in DNA. But RNA does not have T
What term is defined by information for one protein in eukaryotes
monocistronic
Which part of the mRNA serves as a recognition feature for initiation factor binding? What stabilizes mRNA and contributes to initiation of translation?
5'cap; 3' poly A tail
What aspect of RNA makes it more susceptible to chemical hydrolysis than DNA?
2'OH of ribose
Bacterial ribosomes are ___S, eukaryotic ribosomes are __S
70; 80
True or false: RNA only shows canonical base pairing.
FALSE- it may show non-canonical (NON WATSON CRICK) base pairing
Where is the 5' cap? Where is the poly A tail?
BONUS: explain cap snatching
The cap is placed before the start codons and introns, the poly a tail is placed after the stop codon
BONUS: many viruses, like the flu, will transfer 7-meG from the host mRNA to their viral mRNA to stabilize their own mRNA and increase translation efficiency (do not get detected by host surveillance mechanisms)
Explain reverse transcription in retroviruses.
Retrovirus has a RNA genome that is single stranded. Once in host cell, uses its own reverse transcriptase to produce DNA from its own RNA genome. There are 3 components: RNA-dependent DNA polymerase, RNaseH, and DNA-dependnt DNA polymerase. The new DNA gets integrated into the host DNA via integrase, now called provirus. The host cell treats this viral DNA as a part of their own genome producing proteins required to assemble new copies of virus
What linkage is important for Eukaryotic mRNA 5' capping?
5'-5' triphosphate linkage
Where would you find E,P, and A sites and what do they do?
On rRNAs and they are sites where polypeptides bind in the ribosome during translation
Which RNA does not code for a protein that is longer than 200 nucleotides?
Long non-coding RNAs aka lncRNAs
Explain the difference between prokaryotic and eukaryotic mRNA
Prokaryotes- polycistronic, no processing of nascent mRNA, transcription is continuous with translation
Eukaryotes- monocistronic, nascent mRNA is processed transcription and translation occur in separate compartments
Explain how the mRNA coronavirus vaccine works.
In complementary regions of RNA, what structures are found?
secondary and tertiary
The secondary structure for rRNA is
hairpin
Where would you find an anticodon? What is the function?
On the anticodon arm of a tRNA; it recognizes and base pairs with a specific codon in mRNA
What does polycistronic mean?
It as one regulatory sequences for multiple genes in the vicinity
The antiviral drug Remdesivir inhibits RNA dependent RNA polymerase (RdRP) of COVID 19. What does it do?
It stalls RNA synthesis. This makes sense because RdRP is vital for viral replication. Without it you can't make new things
A mutation in a gene inhibits the ability for the RNA to participate in mRNA splicing. What is affected? What is the result?
snRNAs- cannot properly remove introns
Where would you find untranslated regions? Prokaryotic or eukaryotic?
Eukaryotic
Which type of RNA is most stable and helps tRNA? How?
rRNA: it provides the environment for anticodons from tRNA to recognize a codon in mRNA
It also catalyzes formations of peptide bonds between each amino acid of a peptider
rRNA plays both structural and catalytic roles in the ribosome
In cells infected with influenza virus, they inhibit host translation. How could they do this?
The viral protein NS1 sequesters and inhibits 3' end cleavage and polyadenylation of the host pre-RNA thus inhibiting host translation
What is the goal of Paxlovid?
It is a combination of nirmatrelvir and ritonavir. Nirmatrerlvir is a protease inhibitor against viral Mpro protease (a protease needed for viral replication) and Ritonavir is a CYP3A4 and pGP inhibitor. The coadministration results in increase nirmatrelvir bioavailability to the target therapeutic range
Which RNA type allows for modifications such as methylation for RNA biogenesis?
small nucleolar RNAs (snoRNAs)
As a researcher, you mutated RdDP domain of reverse transcriptase to make it inactive. What would be the outcome of this mutation on reverse transcription?
4- reverse transcription will be inhibit