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RNA is synthesized by what enzyme? DNA?
- 1.) RNA polymerase
- 2.) DNA polymerase
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RNA is synthesized from what building blocks? DNA?
- 1.) Ribonucleoside triphosphates - NTP's
- 2.) Deoxyribonucleoside triphosphates - dNTP's
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From where are NTP's derived? dNTP's?
- 1.) From the general metabolite pool or from salvaged bases
- 2.) dNTP's are modified NTP's
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True or False?
There is fairly large amount of pre-formed nucleotides in any given cell.
- False.
- Nucleotide synthesis is tightly regulated, and operates in an "on-demand" manner.
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True or False?
Enzymes of NTP synthesis are the targets of cancer chemotherapy.
- False.
- dNTP's are the targets of chemotherapy.
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What are the two major pathways for nucleotide synthesis?
- 1.) The salvage pathway
- 2.) The de novo pathway
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The salvage pathway can produce which types of bases?
The salvage pathway recycles purines from used nucleic acids.
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The de novo pathway can produce which types of bases?
Synthesis from scratch of:
- 1.) Purines
- 2.) Pyrimidines
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How is a ribonucleoside monophosphate converted to an NTP?
Kinases transfer a phosphate from ATP in two different reactions, yielding two ADP and one NTP.
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Identify the following molecule:
5-Phosphoribosyl-1-pyrophosphate (PRPP).
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What function does PRPP serve?
It is the source of the ribose sugar in both pathways.
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HGPRTase synthesizes _________ or __________ from hypoxathine or guanine and PRPP.
- 1.) Inosinate (IMP) +PPi
- 2.) Guanylate (GMP) + PPi
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IMP can be converted to ________ or ________.
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APRTase synthesizes _________ from adenine and PRPP.
Adenylate (AMP) + PPi.
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Translate "de novo."
"From scratch."
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Which pathway constructs bases from general metabolic building blocks?
The de novo pathway.
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De novo purine synthesis produces which of the nucleosides?
Inositol monophosphate (IMP), which is then converted to AMP or GMP.
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Where is the ribose sugar derived from in de novo synthesis?
PRPP.
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What is significant about PRPP and de novo synthesis of purines?
The base structure is built on PRPP from the beginning, rather than adding the ribose later.
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Pyrimidine de novo synthesis produces which nucleoside?
UMP.
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In the pyrimidine de novo pathway, aminating UTP yields _________.
CTP.
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Why isn't TMP an end product of the pyrimidine de novo pathway?
The salvage and de novo pathways produce nucleotides for RNA, not DNA. Thymine is unique to DNA.
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Which pathway(s) requires one-carbon units provided by tetrahydrofolate?
- 1.) De novo synthesis of purines2.) synthesis of dTTP
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Tetrahydrofolate can be classified as a ____1____, and is derived from the vitamin ____2____.
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True or False?
Tetrahydrofolate has a site that specifically binds carbon in the form of a methyl-fucntional group.
- False.
- Tetrahydrofolate carries one-carbon units in many different forms. They can have different oxidation states, and they maintain these states after transfer.
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Identify the carbon binding site:
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True or False?
Due to its high demand, nucleotide synthesis generally does not require feedback inhibition.
- False.
- Regulation occurs "at the first reaction and at branches."
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Product A typically (activates / inhibits) pathway A, while at the same time (activates / inhibits) pathway B.
- 1.) Inhibits
- 2.) Activates
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