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biochem exam 4 > Nucleotides > Flashcards

Nucleotides Flashcards

1
Q

What is DNA?

A

Deoxyribonucleic acid

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2
Q

What is RNA?

A

Ribonucleic acid

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3
Q

What is rRNA?

A

ribosomal RNA

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4
Q

What is mRNA?

A

messenger RNA

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5
Q

What is tRNA?

A

transfer RNA

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6
Q

What the are three components of a nucleotide?

A

a nitrogenous base
a pentose
1+ phosphate

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7
Q

what is a nucleoside?

A

the molecule without the phosphate group?

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8
Q

What is a pyrimidine?

A

6 membered ring

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9
Q

What is a purine?

A

6 membered ring fused with a 5 membered ring

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10
Q

what are the major purine bases?

A

adenine (A) in DNA and RNA
guanine (G) in DNA and RNA

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11
Q

what are the major pyrimidine bases?

A

cytosine (C) in DNA and RNA
thymine (T) only DNA
uracil (U) only RNA

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12
Q

what are deoxyribonucleotides?

A

structural units of DNA

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13
Q

what ribonucleotides?

A

structural units of RNA

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14
Q

what are the two pathways that lead to nucleotides?

A

de novo pathways
salvage pathways

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15
Q

what are de novo pathways?

A

begin with metabolic precursors: amino acids, ribose 5-phosphate, CO2 and NH3

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16
Q

Bases in de novo are synthesized while attached to what?

A

a ribose

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17
Q

pyrimidine ring is synthesized as

A

orotate

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18
Q

Glutamine provides most:

A

amino groups

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19
Q

Glycine is the precursor for:

A

purines

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20
Q

Aspartate is the precursor for:

A

pyrimidines

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21
Q

what molecule is an important part of both purine and pyrimidine synthesis

A

PRPP

22
Q

what are salvage pathways?

A

recycle the free bases and nucleosides released from nucleic acid breakdown

23
Q

What is the Starting point in purine synthesis?

A

PRPP (ribose sugar w/phosphate attached)

24
Q

What is the end point in purine synthesis?

A

Inosinate (IMP) is the first intermediate with a complete purine ring

25
Q

From IMP can form either:

A

adenylate or guanylate

26
Q

In the biosynthesis of AMP and GMP from IMP what donates amino group for adenylate (AMP)?

A

aspartate

27
Q

In the biosynthesis of AMP and GMP from IMP what donates amino group for guanylate (GMP)?

A

Glutamine

28
Q

What intermediate is formed in AMP formation?

A

fumarate

29
Q

Regulation of AMP/GMP Synthesis is generalized or specific?

A

specific regulation of either one or the other

30
Q

What are the 3 inhibitors of AMP GMP formation, what is specific for GMP?

A

AMP GMP and IMP
GMP is specific for GMP

31
Q

What is the first release intermediate in the salvage of AMP?

A

Hypoxanthine

32
Q

What is the first release intermediate in the salvage of GMP?

A

Guanine

33
Q

Pyrimidine synthesis proceeds by first making:

A

a pyrimidine ring in the form of orotate

34
Q

What is attached after pyrimidine ring formation?

A

ribose 5-phosphate

35
Q

What provides atoms for the ring structure?

A

aspartate and carbamoyl phosphate

36
Q

Pyrimidine synthesis starts with:

A

Aspartate and carbamoyl phosphate

37
Q

Is pyrimidine synthesis specific or generalized?

A

generalized

38
Q

What inhibits pyrimidine synthesis?

A

Cytidine 5’-triphosphate (CTP)

39
Q

What is the general pathway from pyrimidine synthesis?

A

Aspartate and carbamoyl phosphate react and eventually form orotate, PRPP adds orotate at the C-1 position, forming Uridylate (UMP), ATP converts to Uridine 5’-triphosphate (UTP), uracil to cysteine added a glutamine by ATP forming cytidine 5’-triphosphate (CTP)

40
Q

Deoxyribonucleotide Synthesis requires:

A

ribonucleotide reductase and NADPH

41
Q

What does ribonucleotide reductase do?

A

removal of hydroxyl group at position 2 and replaces with a hydrogen

42
Q

thymidylate synthesis requires?

A

Folate (Vitamin B9)

43
Q

What is the primary precursor for thymidylate synthesis?

A

dUMP

44
Q

Folic Acid Deficiency leads to reduced?

A

Thymidylate Synthesis

45
Q

Folic acid deficiency occurs in approximately what percentage of the population and what percentage of impoverished countries?

A

~10% of population
~50% of impoverished countries

46
Q

Reduced thymidylate synthesis causes?

A

Uracil to be incorporated into DNA

47
Q

Repair mechanisms remove the uracil by?

A

Creating strand breaks that affect the structure and function of DNA

48
Q

What is thymidylate synthesis associated with?

A

cancer, heart disease, and neurological impairment

49
Q

catabolism of pyrimidines leads to production of what?

A

NH4+

50
Q

Carbons of thymine are degraded to?

A

succinyl coA

51
Q

Carbons of cytosine and uracil are degraded to?

A

Acetyl coA

52
Q

Where does the nitrogen groups from catabolism of pyrimidines go?

A

urea production

biochem exam 4 (3 decks)

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