Exam 4 Review Flashcards
Which of the following is not a similarity between the replicative DNA polymerase and the RNA polymerase used in transcription?
a. both require nucleoside triphosphates
b. both polymerize in the 5’ to 3’ direction
c. both require templates
d. both require primers to initiate new strand synthesis
e. all of the above are traits of both
f. none of the above are shared traits
d
which of the following is not true of bacterial translation?
a. the process is energy-demanding, but done more quickly compared to eukaryotes
b. the first tRNA is placed within the P site of the ribosome of the 50S subunit
c. 23S rRNA is responsible for catalyzing the transpeptidation
d. fewer initiation/elongation factors are used as compared to eukaryotes
e. all of the above are true
f. none of the above are true
e
T/F: in bacteria there tends to be one sigma factor used for transcription, but alternative factors are usually required for special circumstances
true
T/F: all 64 codons of the genetic code encode for amino acids
false
T/F: 5S rRNA is found in the large ribosomal subunit of both prokaryotes and eukaryotes
true
T/F: polysomes are observed in all three domains to improve the efficiency of translation
true
Important to the DNA replication process is separating two strands of the DNA chromosomes; please provide the 3 proteins within the replisome that are imperative in this role.
origin binding proteins
single stranded binding proteins
helicases
In bacteria, how is DNA polymerase I different in enzymatic activity from DNA polymerase III?
DNA polymerase I uses 5’ to 3’ exonuclease activity
To complete the replication of a bacterial chromosome __________ proteins bind to _________ sites that are found on the opposite side of the chromosome from the origin of replication. Ultimately, the chromosomes are separated and bind to _______, a component within the divisome
Tus
Ter
FtsK
Plasmids replicate using the ________________ method
rolling circle
The consensus sequence, TATAAT, located _______ (#) bases upstream of the bacterial transcription start site is called the _____________. a second consensus sequence _______, is located 35 bases upstream of the bacterial transcription start site.
10
Pribnow box
GGTACA
T/F: archaeal microorganisms contain these same promoter sequences for thei transcriptional processes
False
In the intrinsic method of terminating transcription, the DNA at the end of the gene will be GC-rich and contain inverted repeats followed by a stretch of adenines - how do these sequences affect mRNA structure and contribute to the termination of transcription?
Hydrogen bonding between GC rich segments within the mRNA sequence forms a hairpin loop which destabilizes the interaction between RNA polymerase and the RNA transcript.
The inverted repeats on the RNA form a stem loop structure that further stabilizes the hairpin formation. In the transcribed RNA, there is a stretch of uracils (as a result of transcribing adenine). This forms a poly-U which destabilizes the RNA polymerases interaction with the DNA template.
One unique characteristic regarding bacterial mRNA is that it is ________ which means it contains multiple genes. Please explain how the eventual proteins are seperated?
polycistronic
Please provide three characteristics that define mRNA transcripts within eukaryotes but are not shared by bacteria
monocistronic
3’ end (Poly A tail)
5’ cap (7-methylguanosine)
________________ are the enzymes responsible for charging individual tRNA molecules with the appropriate amino acid. The amino acid is always added to the 3’ acceptor site which ends with the sequence ____________
aminoacyl-tRNA synthetase
CCA
Provide one reason why tRNA is more stable than mRNA
the secondary (clover leaf) structure with intradomain bends
The shine dalgarno sequence is located within the __________ of the mRNA transcript at the ___ end
leader sequence
5’
what does the shine-dalgarno sequence specifically bind to?
5’ end of 16S rRNA
T/F: the Shine-Dalgarno sequence is uniquely found within prokaryotes
True
T?F: IF-3 binds to the large ribosomal subunit to prevent it binding the small subunit too early
false
what are the two roles of IF-2 in the initiation of bacterial translation
Brings the first tRNA to the P site
Binds GTP and guides it to the 30S subunit to be hydrolyzed once the 50S subunit is bound, allowing the initiation complex to be formed
Please explain how tRNAs are brought into the A site during bacterial translation (you must provide the correct elongation factors and thei roles)
EF-Tu will bring the tRNA into the A site, and GTP will be recycled by EF-Ts. The 23S rRNA will complete the peptid linkage and EF-G will facilitate translocation of the ribosome to the P site
T/F: bacterial proteins begin to fold before the peptide synthesis is complete while eukaryotes tend to wait until synthesis is finished
False
