Practice Questions

  1. Home
  2. Free Resources
  3. Practice Questions
  4. 55397
TLS Online TPP Program

#Question id: 1385

The ability of a population of fibroblasts to migrate along the surface of a tissue culture dish depends on adhesion between the cell surface and the extracellular matrix molecules coating the dish. The dish is coated with laminin, and the only cell-surface protein capable of binding laminin is a cell-adhesion protein called an integrin. Integrins are integral plasma-membrane proteins that function as heterodimers. Under these conditions the rate at which a fibroblast can migrate along the laminin coated culture dish is proportional to the strength of adhesion between the cell and the laminin substrate. The table below lists the rate of cell migration observed for fibroblasts genetically engineered to generate the indicated phenotypes.

 Which of the following is the most likely explanation for failure of overexpression of the integrin alpha subunit to alter the rate of fibroblast migration?

#Unit 4. Cell Communication and Cell Signaling

  1. The integrin alpha subunit is not required for integrin function.

  2. The integrin alpha subunit cannot function without a beta subunit.

  3. The integrin alpha subunit binds a cytoplasmic protein factor necessary for integrin function.

  4. The integrin alpha subunit alone is functional, but the cell proteolytically destroys the excess integrin alpha subunits.

More Questions
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: 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: 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: 654

#Unit 1. Molecules and their Interaction Relevant to Biology

Which pair represents different conformations?
TLS Online TPP Program

#Question id: 655

#Unit 1. Molecules and their Interaction Relevant to Biology

A change from one conformation of a molecule to another involves ________.
TLS Online TPP Program

#Question id: 656

#Unit 1. Molecules and their Interaction Relevant to Biology

The ________ is the single shape a protein adopts under physiological conditions.