Purines and Pyrimidines

Descripción

CMB Final Test sobre Purines and Pyrimidines , creado por Peter Seymour el 18/09/2014.
Peter Seymour
Test por Peter Seymour, actualizado hace más de 1 año
Peter Seymour
Creado por Peter Seymour hace alrededor de 10 años
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Resumen del Recurso

Pregunta 1

Pregunta
A rapidly dividing cell will have a greater abundance of which nucleotide?
Respuesta
  • Guanine and Adenine because purine synthesis is more important for a developing cell
  • Cytosine and Thiamine because pyrimidine synthesis is less taxing and therefore proceed more quickly
  • The concentration of pyrimidines and purines will be equal regardless of the conditions
  • Purines are critical for DNA replication, so purine concentration will be higher

Pregunta 2

Pregunta
Which of the following is a nucleotide?

Pregunta 3

Pregunta
For the previous question why was the correct answer the only nucleotide?
Respuesta
  • It was the only answer that consisted of a nucleoside bound to a phosphate group
  • All of the other answers were sugars
  • All of the other answers were bases
  • None of the other answers were biologically important molecules

Pregunta 4

Pregunta
Which of the following is not a biological function of Nucleotides?
Respuesta
  • They are precursors to glycogen and other phosphoglycerides
  • Nucleotides exclusively compromise the universal energy currency
  • They serve as metabolic regulators and mediate the action of many hormones
  • Nucleotides entirely make up three major co-enzymes: NADH, FAD, and CoA

Pregunta 5

Pregunta
cAMP is a nucleotide that mediates hormones
Respuesta
  • True
  • False

Pregunta 6

Pregunta
Purine biosynthesis involves which of the following precursors?
Respuesta
  • Glycine
  • Glutamine
  • Aspartate
  • carbon dioxide
  • Formyltetrahydrofolate
  • All of the above are required atom contributors

Pregunta 7

Pregunta
PRPP (Phosphoribosylpyrophosphate) is the source of the ribose sugar in...
Respuesta
  • purine de novo synthesis and purine salvage pathways
  • purine de novo synthesis
  • purine salvage
  • purine and pyrimidine de novo synthesis

Pregunta 8

Pregunta
Which describes the committed step for purine de novo synthesis?
Respuesta
  • Glutamine-PRPP amido-transferase is the active enzyme
  • PRPP feeds into the committed step
  • Glutamine feeds into the step and becomes glutamate
  • All of the above

Pregunta 9

Pregunta
THF is an enzyme that performs which of the following actions?
Respuesta
  • Eliminates an amide group
  • Transfers one carbon from N10-Formyl THF to the growing purine precursor
  • Allosterically activates HGRPT
  • Facilitates a Glutamine dependent nitrogen tranfer
  • Facilitates ring closure of the growing purine

Pregunta 10

Pregunta
The base hypoxanthine is described by which of the following statements?
Respuesta
  • Inosinic Acid (IMP) is the nucleoside form of hypoxanthine
  • Hypoxanthine is critical only to the conversion of IMP to GMP not IMP to AMP
  • Hypoxanthine is reduced to xanthine during the purine synthesis pathway
  • The oxidation of hypoxanthine to xanthine is blocked by allpurinol

Pregunta 11

Pregunta
PRPP impacts which of the following?
Respuesta
  • De novo synthesis of purines
  • Direct production of IMP through PRPP's reaction with Hypoxanthine
  • Direct production of GMP through PRPP's reaction with Guanine
  • All of the above are catalyzed by HGPRT and all are true in healthy cells

Pregunta 12

Pregunta
Which of the following is deficient in Gout?
Respuesta
  • HGPRT
  • ADA (adenosine deaminase)
  • PNP (purine nucleoside phosphorylase)
  • You have to be more specific, gout could be the result of numerous enzyme deficiencies
  • XO (xanthine oxidase)

Pregunta 13

Pregunta
Lesch Nyhan Syndrome is caused by a deficiency in which of the following?
Respuesta
  • PRPP
  • XO (xanthine oxidase)
  • ADA (adenosine deaminase)
  • HGPRT
  • You have to provide more information, Lesch Nyhan Syndrome could be caused by the deficiency of a number of different enzymes

Pregunta 14

Pregunta
Which is the committed step of Pyrimidine synthesis?
Respuesta
  • Aspartate Transcarbamoylase ATCase
  • Dihydroorotase
  • OPRT
  • CTP synthetase

Pregunta 15

Pregunta
Familial Orotic Aciduria can be treated using which of the following methods?
Respuesta
  • There is no curative treatment, simply a management of symptoms
  • Delivery of large doses of orally administered uridine to simply bypass the early steps of pyrimidine synthesis
  • Delivery of large doses of the missing/deficient orotate phosphoribosyltransferase (OPRT)
  • Delivery of fully synthesized pyrimidines for uptake into the cell

Pregunta 16

Pregunta
Which of the following are made by a two enzyme complex (Thymidylate Synthetase and Dihydrofolate reductase) after ribonucleotide reductase acts on freshly minted purines and pyrimidines?
Respuesta
  • dADP
  • dGDP
  • dCDP
  • dUDP
  • dTTP

Pregunta 17

Pregunta
dATP is the master negative regulator of Ribonucleotide Reductase.
Respuesta
  • True
  • False

Pregunta 18

Pregunta
Which of the following enzymes should I know really well?
Respuesta
  • Ribosomyl Reductase
  • PRPP Synthetase
  • Xanthine Oxidase
  • Dihydrofolate Reductase
  • HGPRT
  • Amidophosphoryl Transferase ATase = glutamine PRPP amidotransferase
  • I should probably know all of these

Pregunta 19

Pregunta
Why do we use "De Novo" instead of saying from scratch?
Respuesta
  • Because Carl Sagan's famous Apple Pie from scratch comment makes it too awesome to use in any setting other than musing about the universe
  • Because De Novo is more descriptive
  • To confuse those who are sadly lacking in medical jargon
  • Because fancy language is awesome
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