Genetics 5

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Genetics 5
2010-02-15 13:49:02
genetics 5 usp james donaldson bruist

Genetics 5
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  1. RNA is synthesized by what enzyme? DNA?
    • 1.) RNA polymerase
    • 2.) DNA polymerase
  2. RNA is synthesized from what building blocks? DNA?
    • 1.) Ribonucleoside triphosphates - NTP's
    • 2.) Deoxyribonucleoside triphosphates - dNTP's
  3. 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
  4. 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.
  5. True or False?
    Enzymes of NTP synthesis are the targets of cancer chemotherapy.
    • False.
    • dNTP's are the targets of chemotherapy.
  6. What are the two major pathways for nucleotide synthesis?
    • 1.) The salvage pathway
    • 2.) The de novo pathway
  7. The salvage pathway can produce which types of bases?
    The salvage pathway recycles purines from used nucleic acids.
  8. The de novo pathway can produce which types of bases?
    Synthesis from scratch of:

    • 1.) Purines
    • 2.) Pyrimidines
  9. 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.
  10. Identify the following molecule:
    5-Phosphoribosyl-1-pyrophosphate (PRPP).
  11. What function does PRPP serve?
    It is the source of the ribose sugar in both pathways.
  12. HGPRTase synthesizes _________ or __________ from hypoxathine or guanine and PRPP.
    • 1.) Inosinate (IMP) +PPi
    • 2.) Guanylate (GMP) + PPi
  13. IMP can be converted to ________ or ________.
    • 1.) AMP
    • 2.) GMP
  14. APRTase synthesizes _________ from adenine and PRPP.
    Adenylate (AMP) + PPi.
  15. Translate "de novo."
    "From scratch."
  16. Which pathway constructs bases from general metabolic building blocks?
    The de novo pathway.
  17. De novo purine synthesis produces which of the nucleosides?
    Inositol monophosphate (IMP), which is then converted to AMP or GMP.
  18. Where is the ribose sugar derived from in de novo synthesis?
  19. 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.
  20. Pyrimidine de novo synthesis produces which nucleoside?
  21. In the pyrimidine de novo pathway, aminating UTP yields _________.
  22. 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.
  23. Which pathway(s) requires one-carbon units provided by tetrahydrofolate?
    • 1.) De novo synthesis of purines
    • 2.) synthesis of dTTP
  24. Tetrahydrofolate can be classified as a ____1____, and is derived from the vitamin ____2____.
    • 1.) Cofactor
    • 2.) Folate
  25. 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.
  26. Identify the carbon binding site:
  27. 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."
  28. Product A typically (activates / inhibits) pathway A, while at the same time (activates / inhibits) pathway B.
    • 1.) Inhibits
    • 2.) Activates