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TLS Online TPP Program

#Question id: 2589

Following statements are regarding to the mechanism of thick filament regulation.

A. In vertebrate smooth muscle, phosphorylation of the myosin regulatory light chain (LC) activates contraction.

B. At Ca2+ concentrations of more than 10−6 M, the regulatory light chain is not phosphorylated, and the myosin adopts a folded conformation.

C. When the Ca2+ level rises, Ca2+ binds calmodulin (CaM), which undergoes a conformational change (CaM*). The CaM*-Ca2+ complex binds and activates myosin light chain kinase (MLC kinase), which then phosphorylates the myosin LC. This phosphorylation event unfolds the myosin II, which is now active and can assemble into bipolar filaments to participate in contraction.

D. When the Ca2+ levels drop, the myosin LC is dephosphorylated by myosin light-chain (MLC) phosphatase, which is dependent on Ca2+ for activity, causing muscle relaxation.

Which of the following combination is correct?

#Unit 2. Cellular Organization

  1. A, B and C

  2. A, C and D

  3. A and C only

  4. B and D only

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TLS Online TPP Program

#Question id: 15905

#Unit 12. Applied Biology

Meristemoids are considered to arise in areas that accumulate polysaccharide, which is believed to serve as an energy source for shoot bud differentiation
TLS Online TPP Program

#Question id: 2917

#Unit 2. Cellular Organization

With respect to the interconversion between open and condensed chromatin shown below: Which of the directions (i) or (ii) would you anticipate would be the consequence of the following types of chromatin modification?
TLS Online TPP Program

#Question id: 28852

#Unit 2. Cellular Organization

Which of the following proteins are End-Binding Proteins?
a) XMAP215
b) Op18
c) Kinesin-13
d) stathmin
TLS Online TPP Program

#Question id: 19919

#Unit 13. Methods in Biology

Scatchard plots are based on repeated equilibrium dialyses with a constant concentration of antibody and varying concentration of ligand. Which plots correctly verify the Scatchard equation that determined by equilibrium dialysis?
TLS Online TPP Program

#Question id: 26839

#Unit 10. Ecological Principles

Species within a community that has a role out of proportion to its abundance are called___