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TLS Online TPP Program

#Question id: 863

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

#Unit 1. Molecules and their Interaction Relevant to Biology

  1. A hollow cylindrical core, known as the 20S proteasome, which is covered at one or both ends by a 19S cap.

  2. The yeast 20S proteasome, which is closely similar to other eukaryotic 20S proteasomes, is composed of Ten different types of α-like subunits.

  3. The yeast 20S proteasome, which is closely similar to other eukaryotic 20S proteasomes, is composed of seven different types of α-like subunits and seven different types of β-like subunits.

  4. The α-type subunits and the β-type subunits are structurally similar, only three of the β-type subunits have proteolytic activity.

    Choose any one incorrect option.

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TLS Online TPP Program

#Question id: 2425

#Unit 2. Cellular Organization

Which of the following is (are) actin-based structures?

a. adherins belt                        b. contractile ring        c. mitotic spindle

d. nuclear lamina         e. stress fibers
TLS Online TPP Program

#Question id: 2426

#Unit 2. Cellular Organization

Actin assembly in vitro

a. consists of three phases.     

b. requires addition of actin oligomers termed nuclei.

c. requires ATP hydrolysis.

d. is reversible.

e. requires actin-binding proteins.
TLS Online TPP Program

#Question id: 2427

#Unit 2. Cellular Organization

Known functions of actin-binding proteins include

a. severing of long filaments to generate shorter filaments.

b. inhibition of filament polymerization.                   

c. bundling of filaments.

d. acceleration of filament polymerization rates.

e. capping of the (+) end.
TLS Online TPP Program

#Question id: 2428

#Unit 2. Cellular Organization

Which of the following prevent(s) acting disassembly?

a. cytochalasin D         b. jasplakinolide          c. latrunculin               d. phalloidin
TLS Online TPP Program

#Question id: 2429

#Unit 2. Cellular Organization

Which of the following statements is (are) true of actin assembly?

a. ADP-actin can assemble into filaments.    

b. Actin (+) ends grow faster than actin (-) ends.

c. ATP-actin can assemble into filaments.

d. Toxins that alter the assembly of actin filaments have been used as tools to study actin in living cells.
TLS Online TPP Program

#Question id: 2430

#Unit 2. Cellular Organization

Actin-binding proteins that generate actin filament bundles: