TLS Online TPP Program

#Question id: 2870


In Escherichia coli, the synthesis of tryptophan is controlled by the tryptophan operon that is repressed in the presence of excessive tryptophan. When a mutant strain that has lost the regulatory gene of the tryptophan operon is placed in a medium that contains all nutrients the cells need to grow except tryptophan, which of the following will occur?

#Unit 2. Cellular Organization
  1. The cells will continue to grow even though excess tryptophan is synthesized.

  2. The cells will grow until excessive tryptophan arrests the expression of the operon.

  3. The cells will not grow until enough tryptophan has been synthesized to activate the corepressor.

  4.  The cells will never grow unless tryptophan is added to the medium.

More Questions
TLS Online TPP Program

#Question id: 858

#Unit 1. Molecules and their Interaction Relevant to Biology

Unfolded protein response (UPR)

TLS Online TPP Program

#Question id: 859

#Unit 1. Molecules and their Interaction Relevant to Biology

Which one statement is incorrect about ATG genes;

TLS Online TPP Program

#Question id: 860

#Unit 1. Molecules and their Interaction Relevant to Biology

Select true ‘T’ AND false ‘F’ about ubiquitinylation

I. These ubiquitin-like modifiers control processes as diverse as nuclear import,

II. Regulated by the ubiquitin-like modifier Sumo, and autophagy,

III. Regulated by the ubiquitin-like modifier Atg8.

IV. For a protein to be efficiently degraded, it must be linked to a chain of at least four tandemly linked ubiquitin molecules in which Lys 34 of each ubiquitin forms an isopeptide bond with the C-terminal carboxyl group of the following ubiquitin.

TLS Online TPP Program

#Question id: 861

#Unit 1. Molecules and their Interaction Relevant to Biology

Alexander Varshavsky discovered, the half-lives of many cytoplasmic proteins vary with the identities of their N-terminal residues via the so-called N-end rule:-

A. Destabilizing N-terminal residues Asp, Arg, Leu, Lys, and Phe have half-lives of

i. Only 2 to 3 minutes,

B. Stabilizing N-terminal residues Ala, Gly, Met, Ser, Thr, and Val have half-lives of

ii. >10 hours in prokaryotes

iii. >20 hours in eukaryotes.

TLS Online TPP Program

#Question id: 862

#Unit 1. Molecules and their Interaction Relevant to Biology

Match the following

lysosomal protein degradation pathways

         Found in

1. Nonselective

a-well-nourished cells

i-containing the pentapeptide Lys-Phe-Glu-Arg-Gln

2- Selective

b-starving cells

TLS Online TPP Program

#Question id: 863

#Unit 1. Molecules and their Interaction Relevant to Biology

Ubiquitinated proteins are proteolytically degraded in an ATP-dependent process mediated by a large (∼2500 kD, 26S) multiprotein complex named the 26S proteasome;