The enzyme aldolase, catalyzes a reversible aldol condensation, Fructose 1,6-bisphosphate is cleaved to yield two different triose phosphates, glyceraldehyde 3-phosphate, an aldose, and dihydroxyacetone phosphate, a ketose. There are two classes of aldolases such as;

A) Class I aldolases

B) Class II aldolases

i) Found in animals and plants

ii) Found in in fungi and bacteria

iii) formation of protonated Schiff base on enzyme and its active site contain lysine residue

iv) do not form the Schiff base intermediate and a zinc ion at the active site is coordinated with the carbonyl oxygen at C-2

In which of the following option is the given enzyme with its correct statements?

TLS Online TPP Program

#Question id: 14760

#Unit 2. Cellular Organization

During the microfilament formation, the nucleation phase is marked by:

TLS Online TPP Program

#Question id: 14761

#Unit 2. Cellular Organization

Following graph represent phases of in vitro G-actin polymerization.

Which of the following is correct?

TLS Online TPP Program

#Question id: 14762

#Unit 2. Cellular Organization

Following statements are regarding to determination of filament formation by actin concentration.

A. The critical concentration (Cc) is the concentration at which G-actin monomers are in equilibrium with actin filaments.

B. At monomer concentrations below the Cc, no polymerization takes place. 

C. When polymerization is induced at monomer concentrations above the Cc, filaments assemble until steady state is reached and the monomer concentration falls to Cc.

D. At steady state, the concentration of monomeric actin below the critical concentration.

Which of the following statements promotes spontaneous filament assembly?

TLS Online TPP Program

#Question id: 14763

#Unit 2. Cellular Organization

Which of the following graph shows G-actin polymerize into F-actin.

 

TLS Online TPP Program

#Question id: 14764

#Unit 2. Cellular Organization

Match the following proteins (Column I) with their function (Column II). Which of the following is correct?

Column I	Column II
a. Profilin	i. binds to the (+) end of an actin filament, thereby inhibiting subunit addition or loss.
b. Cofilin	ii. blocks (−) ends, inhibits filament disassembly, to stabilize filaments
c. Thymosin-β4	iii. involved in actin treadmilling, but it binds specifically to F-actin in which the subunits contain ADP
d. Cap Z	iv. binds ADP–G-actin and catalyzes the exchange of ADP for ATP
e. Tropomodulin	v. binds to ATP–G-actin in such a way that it inhibits addition of the actin subunit to either end of the filament.

TLS Online TPP Program

#Question id: 14765

#Unit 2. Cellular Organization

Following statements are regarding to the formins which involve in filament assembly.

A. All formin family members have two adjacent domains in common, the so called FH1 and FH2 domains (formin-homology domains 1 and 2).

B. Two FH2 domains from two individual formin monomers associate to form a doughnut-shaped complex can form a dimer and nucleate filament assembly.

C. The FH1 domain of formin is rich in proline residues, which serve as sites for the binding of several profilin molecules.

D. The FH2 domain behaves as a landing site for profilin–ATP–G-actin to increase the local concentration of these complexes.

E. Formins are activated by membrane bound Rho-GTP, a Ras-related small GTPase.

Which of the following combination is correct?