#Question id: 4290
#Unit 3. Fundamental Processes
23S rRNA catalyze peptide-bond formation explained by the model of proton shuttle given in figure.
Which of the following statements is/are CORRECT for this model?
A. Base pairing between the 23S rRNA and the CCA ends of the tRNAs in the A- and P-sites positions is crucial for this reaction
B. This catalytic mechanism involves entropy
C. 2’-OH of the P-site tRNA act as part of a “proton shuttle”
D. it is a protein that catalyses peptide bond formation
#Question id: 4291
#Unit 3. Fundamental Processes
There are two classes of release factors. Match the following
A. Class I release factors |
1. recognize the stop codons and trigger hydrolysis of the peptide chain from the tRNA in the P-site. |
B. Class II release factors |
2. stimulate the dissociation of the class I factors from the ribosome after release of the polypeptide chain. |
C. RF1 |
3. recognizes the stop codon UAG |
D. RF2 |
4. recognizes the stop codon UGA. |
E. RF1 & RF2 |
5. UAA |
#Question id: 4292
#Unit 3. Fundamental Processes
Termination of prokaryotic translation take place in three set of events. Match the following
A. glycine glycine glutamine, GGQ and RF3-GTP |
1. That is essential for polypeptide release in first step, release of class I RF |
B. RRF & EF-G |
2. the tRNAs and the mRNA must be removed from the ribosome, and the ribosome must dissociate into its large and small subunits. |
C. IF3 |
3. Release of ribosome |
#Question id: 4293
#Unit 3. Fundamental Processes
Match antibiotics with their effects
A. Tetracycline |
1. Inhibits aminoacyl-tRNA binding to A-site in prokaryotes |
B. Chloramphenicol |
2. Blocks correct positioning of A-site aminoacyl-tRNA for peptidyl transfer reaction in prokaryotes |
C. Fusidic acid |
3. Prevents release of EF-G–GDP from the ribosome in prokaryotes |
D. Ricin |
4. Prevents activation of translation factor GTPases in both Prokaryotes and Eukaryotes |
#Question id: 4294
#Unit 3. Fundamental Processes
Not surprisingly, in several instances, the two binding sites for the regulatory ribosomal protein are related to each another. In the case of the S8 ribosomal protein, the two binding sites share substantial similarities. The sequence of the binding site in the mRNA reveals a clear mechanism by which S8 inhibits translation. Which of the following are INCORRECT regarding this mechanism?
A. Free rRNA content in cytoplasm activates ribosomal protein biogenesis
B. RNA-binding proteins regulate their expression by binding to their own mRNAs, including some aminoacyl-tRNA synthetases
C. In case of “NO FREE rRNA” ribosomal protein transcript is efficiently translated by autoregulation process
D. In case of “NO FREE rRNA” ribosomal protein transcript undergoes to autorepression
#Question id: 4295
#Unit 3. Fundamental Processes
Regulating iron levels in the human body is critical. Many proteins use iron as a cofactor, including the oxygen transport proteins hemoglobin and myoglobin. Consistent with the important role of iron in oxygen transport and energy production, a shortage of iron in the human body (called anemia) results in an overall feeling of weakness. On the other hand, excess iron is toxic to cells and can contribute to liver damage, heart failure, and diabetes. The iron-binding protein Ferritin is the major regulator of iron levels in the human body. Which of the following are INCORRECT regarding ferritin?
A. Ferritin translation is regulated by iron-binding proteins called iron regulatory proteins
B. The levels of transferrin, transferrin receptor, are also crucial to cellular iron homeostasis
C. Aconitase regulates synthesis of these three proteins is regulated in response to iron availability
D. apoaconitase, is actually IRE that has ability to bind to specific sequences in the mRNAs for the transferrin receptor and ferritin, thus regulating protein synthesis at the translational level.
E. IRE binding to mRNA increases synthesis of ferritin many folds.