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TLS Online TPP Program

#Question id: 13159

How signaling is involved in ensuring that yeast cells fuse only with cells of the opposite mating type?

#Unit 4. Cell Communication and Cell Signaling
  1. The two cells of opposite mating type (a and alpha) each secrete a certain signaling molecule, which can only be bound by receptors carried on cells of the opposite mating type. Thus, the a mating factor cannot bind to another a cell and cause it to grow toward the first a cell. Only an alpha cell can “receive” the signaling molecule and respond by directed growth.
  2. The two cells of opposite mating type (a and alpha) each secrete a certain signaling molecule, which can only be bound by receptors carried on cells of the same mating type. Thus, the a mating factor can bind to another a cell and cause it to grow toward the first a cell.
  3. The two cells of opposite mating type (a and alpha) each proteins attached to the plasma membrane of one cell can interact directly with cell-surface receptors on adjacent cells. Thus, the a mating factor can directly bind to another a cell and cause it to grow.
  4. The two cells of opposite mating type (a and alpha) each respond to substances that they themselves release.
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TLS Online TPP Program

#Question id: 4263

#Unit 3. Fundamental Processes

For the classes of AATS, which of following statement is correct
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