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TLS Online TPP Program

#Question id: 1220

Many G protein-coupled receptors contain seven transmembrane α-helical domains. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior surface or on the cytosolic surface of the membrane. The loop on the cytosolic side between helices 5 and 6 is usually substantially longer than the others. Where would a coupled G protein most likely interact with this receptor?

#Unit 4. Cell Communication and Cell Signaling

  1. at the amino end

  2. at the carboxyl end

  3. along the exterior margin

  4. at the loop between H5 and H6

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TLS Online TPP Program

#Question id: 30101

#Unit 1. Molecules and their Interaction Relevant to Biology

The formation of dATP for DNA synthesis occurs primarily by:
TLS Online TPP Program

#Question id: 30102

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following would NOT be expected to contribute to hyperuricemia (gout)?
TLS Online TPP Program

#Question id: 30103

#Unit 1. Molecules and their Interaction Relevant to Biology

Direct sources of purine ring atoms in the de novo synthesis of IMP include:
1. glutamine.
2. a component of the tetrahydrofolate one-carbon pool.
3. aspartate.
4. glycine.
TLS Online TPP Program

#Question id: 30104

#Unit 1. Molecules and their Interaction Relevant to Biology

A nucleoside phosphorylase:

1. cleaves a nucleoside with the production of ribose 1-phosphate.
2. is necessary for the major salvage pathway for pyrimidines.
3. is used in the degradation of purine nucleotides.
4. is responsible for the equilibration of nucleoside monophosphates and nucleoside diphosphate.
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.