Exam 3 Quiz Questions Flashcards
Why is ribosomal RNA not spliced as it is processed?
Splicing rejoins RNA after introns are removed
Which posttranslational modification don’t normally increase the stability of mRNAs?
- 5’ methyl G cap
- splicing
- polyA tail
- uracil
Uracil addition
Which is not true about pseudouridylation?
- Box H/ACA direct pseudouridylation by directly basepairing with the target RNA.
- tRNAs are pseudouridylated
- Pseudouridylation decreases the basepairing with adenine
- Proteins direct the pseudouridylation
Pseudouridylation decreases the basepairing with adenine
MicroRNAs
- are ribozymes
- basepair to mRNA to direct methyltion
- basepair to mRNA to direct cleavage
- basepair ot introns to direct splicing
Basepair to mRNA to direct cleavage
What is one reason not contributing to the high rate of retrovirus mutations?
- DNA-dependent DNA synthesis is error prone
- Deamination nucleotides in the RNA genome escape repair
- Retroviruses can cause cancer and cancer is mutagenic
- Polypeptides are cleaved with proteases
Retroviruses can cause cancer and cancer is mutagenic
What is not true about telomerase?
- They contain the RNA sequences called box H/ACA
- The 5’ end of the hTERT serves as the RNA template to extend telomeres
- Telomerase extends the 3’ end of DNA
- Telomerase synthesized both strands of the telomeric DNA
Telomerase synthesized both strands of the telomeric DNA
What is not true about ribosomes?
- levels change during different rates of growth
- they are composed of protein and rRNA assembled in the th enucleolus cotranscriptionally
- they are posttranscriptionally modified by box C/D and H/ACA snoRNAs
- all are true
All are true
RNA editing:
- changed the codon to a stop codon or to a different codon
- increases genetic diversity without changes to the DNA sequence
- can include deamination fo nucleotides
- all of these
All of these
Which step in splicing needs to occur before the spliceosome is considered active?
- the lariat forms
- U1 snRNP disassociates
- the branch site cleaves the 5’ slice site
- ATP is cleaved
- all of these
U1 snRNP disassociates
The canonical start codon is …
AUG
Selenocysteine is a nongenetically encoded amino acid. How is it incorporated into proteins?
A serine charged on a tRNA with a codon that recognizes a stop codon is converted enzymatically to selenocysteine.
Deamination of cytosine to ……..
uracil
If I is in the 5’ end of the anticodon on the tRNA then it will…
basepair with A, U, and C
IF1 is analagous to eIF1A because they both…
bind the A site in the ribosome
As elongation continues in prokaryotes, EF-G…
Moves into the A site as the growinf peptide chain moves to the P site.
Which is not considered a posttranslational modification?
- phosphorylation
- methylation
- farnesylation
- pyrolysine
Pyrolysine
Glycosylation of proteins…
… occurs as proteins are translated directly into the ER.
In bacteria, regulatabel genes tend to be regulated by…
… sigmaS
In bacteria, regulatable genes tend to…
… have activators that bind enhancers.
The Lac repressor…
… physically blocks RNA polymerase from binding to the spot.
DNA binding proteins bind DNA by…
…using free carboxyl and amino groups in amino acid’s R group to hydrogen bond hydrogen and carbons of bases.
Attenuation of the Trp operon transcription uses a similar mechanism to…
… rho-independent termination of transcription (forms a hairpin loop)
The SOS operon is different from the Lac ans Trp operon because…
- it responds to DNA damage rather than presence or absence of a metabolite
- the transcriptional represssor is cleaved when SOS response is activated
- extended SOS response can kill the cell because latent viruses are reactivated
- all of the above
all of the above
The RPG operon is different from Lac, Trp, and SOS operon because…
… the protein product binds their own transcript, inhibiting transcription
The structure that riboswitches take…
… is regulated by the type of metabolite that it binds which usually turns off expression of genes that make that metabolite.
Recombination can move genes in different orientations. In Salmonella, it uses phase variation to…
…increase the phenotypic variation of flagella to evade the host immune system.
Lumafactor was developed to treat the F508del mutation in CFTR. Lumafactor does this by…
… helping in processing of CFTR.
How does the reduced glycosylation of CFTR casue cystic fibrosis?
when CFTR is misfolded N-linked glycosylation is reduced and trafficing from the ER to cell membrane does not happen and the protein is degraded.
Chromatin remodelers…
… slide histones around the DNA
Histone posttranslational modifications are mostly…
reversible
Folate regulates the expression of the Agouti gene by…
methylating and silencing the upstream gene of Agouti and permitting expression of Agouti
Histone code:
- references to the different protein coding sequences of histones
- references to specific sequences that tend to be occupied by histones
- specific combinations of histon PTMs that regulate gene expression
Eukaryotic gene regulation varies from prokaryotic because prokaryotes…
… use different sigma factors to positively regulate transcription.
Hormones such as estrogen induce transcription by…
… binding to DNA-binding proteins to induce dimerization and then bind to promoters.
