Methotrexate is an inhibitor of dihydrofolate reductase. Administration of methotrexate would inhibit:

1. de novo synthesis of UMP.

2. conversion of dUMP to dTMP.

3. conversion of IMP to GMP.

4. de novo synthesis of IMP

TLS Online TPP Program

#Question id: 28829

#Unit 2. Cellular Organization

α-tubulin and β-tubulin comprising 445– 450 amino acids, which are tightly held together by__

TLS Online TPP Program

#Question id: 28830

#Unit 2. Cellular Organization

Each α or β monomer has a binding site for one molecule of GTP, the GTP that is bound to α and β-tubulin.

a) α-tubulin is physically trapped at the dimer interface and is never hydrolyzed

b) α-subunit is at the surface of the dimer and GTP bound by the α-subunit can be hydrolyzed

c) β-tubulin is physically trapped at the dimer interface and it can be hydrolyzed

d) β-subunit is at the surface of the dimer and GTP bound by the β-subunit can be hydrolyzed

Select the correct combination of α and β-tubulin?

TLS Online TPP Program

#Question id: 28831

#Unit 2. Cellular Organization

Most microtubules in a cell consist of a simple tube is called____

TLS Online TPP Program

#Question id: 28832

#Unit 2. Cellular Organization

Most microtubules in a cell consist of a simple tube, a singlet microtubule, built from____

TLS Online TPP Program

#Question id: 28833

#Unit 2. Cellular Organization

Doublet microtubule built from__

TLS Online TPP Program

#Question id: 28834

#Unit 2. Cellular Organization

All microtubules are nucleated from structures known as____