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TLS Online TPP Program

#Question id: 16968

Parallel evolution is a term that has been used to describe cases in which independent evolution of a character state is thought to have similar genetic and developmental bases, especially in closely related species. Which statements is true for

#Unit 11. Evolution and Behavior
  1. Evolutionary reversals constitute a return from a derived character
  2. Distinction between parallel evolution and convergent evolution may be very meaningful because, as we will see, the same gene often contributes to similar evolutionary changes in related organisms.
  3. Distinction between parallel evolution and convergent evolution may not be very meaningful because, as we will see, the same gene often contributes to similar evolutionary changes in distantly related organisms.
  4. Mutational change in a specific gene, Pitx1, is the basis of independent loss of the pelvic girdle and fins in many freshwater populations of a small fish, the three spined stickleback stickleback
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TLS Online TPP Program

#Question id: 4264

#Unit 3. Fundamental Processes

A classic biochemical experiment nicely illustrated the point that the ribosome recognizes tRNA and not the amino acid that it is carrying. In that following observation were made. Which of them can be correct.

A. The cysteine attached to cysteine-tRNACys can be converted to an alanine by chemical reduction to give alanine-tRNACys.

B. Alanine-tRNACys introduces alanines at codons that specify insertion of cysteine.

C. Different mechanism is used to incorporate selenocyteine on tRNA as selenocysteine is incorporated into proteins by chemical modification after translation

D. Selenocysteine is generated enzymatically from serine carried on a special tRNA that is charged by serine-tRNA synthetase

E. Above examples can conclude that the translation machinery relies on the high fidelity of the aminoacyl-tRNA synthetases to ensure the accurate decoding of each mRNA
TLS Online TPP Program

#Question id: 4265

#Unit 3. Fundamental Processes

48S pre initiation complex includes
TLS Online TPP Program

#Question id: 4266

#Unit 3. Fundamental Processes

48S pre initiation complex is
TLS Online TPP Program

#Question id: 4267

#Unit 3. Fundamental Processes

The 3D structure of the complete Escherichia coli ribosome with bound mRNA and tRNAs revealed that the very amino terminus of one protein (L27) does reach into the active site. This finding suggested a role for this protein in catalysis. To test this possibility, the nine amino acids at the L27 amino terminus that were in close proximity to the active site were eliminated by mutation. The following possible outcomes were found to be correct as

A. The resulting cells produced ribosomes with reduced but detectable peptidyl transferase activity

B. Region of the L27 protein contributes to peptidyl transferase activity

C. The mutant ribosomes, didn’t synthesised wildtype levels of cells

D. Vast majority of this increase in peptide bond formation is retained, even without the presence of L27 in the active site

E. The most likely role for L27 is to correctly position one or more of the RNA components of the active site
TLS Online TPP Program

#Question id: 4268

#Unit 3. Fundamental Processes

23S rRNA catalyze peptide-bond formation as

A. base pairing between the 23S rRNA and the CCA ends of the tRNAs

B. A- and P-sites positions the a-amino group of the aminoacyl-tRNA to attack the carbonyl group of the growing polypeptide attached to the peptidyl-tRNA

C. Entropic catalysis is involved
TLS Online TPP Program

#Question id: 4269

#Unit 3. Fundamental Processes

The kinase P-TEFb

A. Is recruited to polymerase by transcriptional activators

B. Phosphorylates the serine 2&5 of the CTD repeats for elongation

C. Phosphorylates SPT5 and TAT-SF1