RNA processing Flashcards
what are the differences between the minor and major grooves of DNA and RNA?
major groove:
DNA- Broader
RNA- Narrower
Minor groove:
DNA- Narrower
RNA- Broader
what is RNA processing?
Collection of events/ modifications that occur to an RNA molecule after it is transcribed from DNA. These modifications are essential for the RNA molecule to function properly
What modifications occur to RNA?
Capping of the 5’ end
Removal of introns (pre- mRNA splicing)
3’ end processing (cleavage and polyadenylation)
what are large RNA’s resolved in?
*think of the gel
agarose gel
what are small RNA’s resolved in?
acrylamide gel
what are majority of RNA’s in a cell?
rRNA (ribosomal RNA)
what are some stable RNAs?
tRNA (Transfer RNA)
rRNA
What is capping of the 5’ end?
Modification that occurs during RNA processing in eukaryotic cells. It involves the addition of a 7-methylguanosine (m7G) cap to the 5’ end of the newly synthesized RNA transcript.
*In essence, capping is like putting a protective cap on the 5’ end of the RNA molecule, ensuring its stability and facilitating its journey through the cell.
What are the protective functions of the cap and poly(A) tail?
They protect the mRNA against degradation and promote translation.
what does the m7G cap of eukaryotic mRNA consist of?
a methylated guanosine nucleotide
What’s the difference between monocistronic and polycistronic mRNA?
monocistronic refers to mRNA that codes for a single gene only - and this type of mRNA is the one present in eukaryotes
polycistronic is the mRNA that encodes for multiple genes at ones - which is the type present in bacterial cells
what are the protein encoding transcripts in bacterial and eukaryotic cells?
monocistronic or polycistronic?
eukaryotes- monocistronic
bacterial- polycistronic
What are “split genes” and how do they differ from prokaryotic genes?
Split genes are found in eukaryotes where protein-coding sequences (exons) are interrupted by non-coding sequences (introns) within the chromosomal DNA. Prokaryotic genes are continuous without introns.
what is the purpose of pre-mRNA splicing?
Its a process that occurs in eukaryotic cells where introns are removed and exons are retained.
pre-mRNA splicing is very precise in order to generate a sequence that can be translated into a protein
describe how pre-mRNA splicing is carried out
Carried out by RNPs called spliceosomes (ribonucleoproteins)
It involves 2 consecutive transesterification reactions
1- the release of 5’ exon and formation of 3’ intron released to the 3’ exon.
2- joins the 2 exons and release intron
