Questão 1
Questão
A rapidly dividing cell will have a greater abundance of which nucleotide?
Responda
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Guanine and Adenine because purine synthesis is more important for a developing cell
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Cytosine and Thiamine because pyrimidine synthesis is less taxing and therefore proceed more quickly
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The concentration of pyrimidines and purines will be equal regardless of the conditions
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Purines are critical for DNA replication, so purine concentration will be higher
Questão 2
Questão
Which of the following is a nucleotide?
Questão 3
Questão
For the previous question why was the correct answer the only nucleotide?
Responda
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It was the only answer that consisted of a nucleoside bound to a phosphate group
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All of the other answers were sugars
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All of the other answers were bases
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None of the other answers were biologically important molecules
Questão 4
Questão
Which of the following is not a biological function of Nucleotides?
Responda
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They are precursors to glycogen and other phosphoglycerides
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Nucleotides exclusively compromise the universal energy currency
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They serve as metabolic regulators and mediate the action of many hormones
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Nucleotides entirely make up three major co-enzymes: NADH, FAD, and CoA
Questão 5
Questão
cAMP is a nucleotide that mediates hormones
Questão 6
Questão
Purine biosynthesis involves which of the following precursors?
Questão 7
Questão
PRPP (Phosphoribosylpyrophosphate) is the source of the ribose sugar in...
Questão 8
Questão
Which describes the committed step for purine de novo synthesis?
Responda
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Glutamine-PRPP amido-transferase is the active enzyme
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PRPP feeds into the committed step
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Glutamine feeds into the step and becomes glutamate
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All of the above
Questão 9
Questão
THF is an enzyme that performs which of the following actions?
Responda
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Eliminates an amide group
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Transfers one carbon from N10-Formyl THF to the growing purine precursor
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Allosterically activates HGRPT
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Facilitates a Glutamine dependent nitrogen tranfer
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Facilitates ring closure of the growing purine
Questão 10
Questão
The base hypoxanthine is described by which of the following statements?
Responda
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Inosinic Acid (IMP) is the nucleoside form of hypoxanthine
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Hypoxanthine is critical only to the conversion of IMP to GMP not IMP to AMP
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Hypoxanthine is reduced to xanthine during the purine synthesis pathway
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The oxidation of hypoxanthine to xanthine is blocked by allpurinol
Questão 11
Questão
PRPP impacts which of the following?
Responda
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De novo synthesis of purines
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Direct production of IMP through PRPP's reaction with Hypoxanthine
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Direct production of GMP through PRPP's reaction with Guanine
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All of the above are catalyzed by HGPRT and all are true in healthy cells
Questão 12
Questão
Which of the following is deficient in Gout?
Responda
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HGPRT
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ADA (adenosine deaminase)
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PNP (purine nucleoside phosphorylase)
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You have to be more specific, gout could be the result of numerous enzyme deficiencies
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XO (xanthine oxidase)
Questão 13
Questão
Lesch Nyhan Syndrome is caused by a deficiency in which of the following?
Responda
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PRPP
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XO (xanthine oxidase)
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ADA (adenosine deaminase)
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HGPRT
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You have to provide more information, Lesch Nyhan Syndrome could be caused by the deficiency of a number of different enzymes
Questão 14
Questão
Which is the committed step of Pyrimidine synthesis?
Questão 15
Questão
Familial Orotic Aciduria can be treated using which of the following methods?
Responda
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There is no curative treatment, simply a management of symptoms
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Delivery of large doses of orally administered uridine to simply bypass the early steps of pyrimidine synthesis
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Delivery of large doses of the missing/deficient orotate phosphoribosyltransferase (OPRT)
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Delivery of fully synthesized pyrimidines for uptake into the cell
Questão 16
Questão
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?
Questão 17
Questão
dATP is the master negative regulator of Ribonucleotide Reductase.
Questão 18
Questão
Which of the following enzymes should I know really well?
Questão 19
Questão
Why do we use "De Novo" instead of saying from scratch?
Responda
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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
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Because De Novo is more descriptive
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To confuse those who are sadly lacking in medical jargon
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Because fancy language is awesome