Which of the following steps has not yet been accomplished by scientists studying the origin of life? 

TLS Online TPP Program

#Question id: 30105

#Unit 1. Molecules and their Interaction Relevant to Biology

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: 30106

#Unit 1. Molecules and their Interaction Relevant to Biology

If a cell has an adequate supply of adenine nucleotides but requires more guanine nucleotides for protein synthesis:

1. Glutamine-PRPP amidotransferase will not be fully inhibited.

2. AMP will be a feedback inhibitor of the condensation of IMP with aspartate.

3. ATP will stimulate the production of GMP from IMP.

4. ATP will inhibit nucleoside diphosphate reductase.

TLS Online TPP Program

#Question id: 30107

#Unit 1. Molecules and their Interaction Relevant to Biology

Major controls of de novo AMP synthesis include:

1. allosteric inhibition by GMP.

2. allosteric inhibition by AMP.

3. availability of PRPP.

4. stimulation by GTP.

TLS Online TPP Program

#Question id: 30108

#Unit 1. Molecules and their Interaction Relevant to Biology

Aspartate plays a role in all of the following EXCEPT:

TLS Online TPP Program

#Question id: 30109

#Unit 1. Molecules and their Interaction Relevant to Biology

Allopurinol is an inhibitor of xanthine oxidase. Administration of allopurinol to a patient with gout and normal HG-PRT levels would be expected to lead to all of the following EXCEPT:

TLS Online TPP Program

#Question id: 30110

#Unit 1. Molecules and their Interaction Relevant to Biology

The ribose phosphate group of purine nucleotide is taken from which compound?