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Biochemistry II > Unit 7 > Flashcards

Unit 7 Flashcards

1
Q

DNA and RNA purines

A

Adenine

Guanine

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2
Q

RNA pyrimidines

A

Cytosine

Uracil

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3
Q

DNA pyrimidines

A

Thymine

Cytosine

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4
Q

Difference between purines and pyrimidines

A

Purines have 2 rings

Pyrimidines have only 1

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5
Q

Nucleosides end will end in

A

-one

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6
Q

Nucleotides will end in:

A

-late

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7
Q

What can synthesize nucleotides in the de novo pathway?

A

Amino acids

Ribose-5-phosphate,

CO2

NH3

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8
Q

In the salvage pathway, nucleotides can be salvages from _______ released from the breakdown of:

A

Nucleobases

Nucleic acids

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9
Q

Compounds that inhibit ______ pathways are promising anti-parasite drugs

A

Salvage

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10
Q

In purine de novo biosynthesis, bases are synthesized while attached to:

A

Ribose

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11
Q

In pyrimidine de novo biosynthesis, only (BEFORE/AFTER) complete synthesis of bases, they are attached to what?

A

Before

Activated sugar 5-phosphoribosyl-1-pyrophosphate (PRPP)

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12
Q

Site of purine synthesis

A

Liver

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13
Q

Amino acids in purine ring

A

Glycine

Aspartate

Glutamine

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14
Q

Major contributors of purine ring

A

Amino acids

CO2

N10- formyl THFf

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15
Q

End products of de novo purine biosynthesis

A

Ribonucleotides

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16
Q

Activator or PRPP synthetase

A

Pi

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17
Q

Inhibitors of PRPP synthetase

A

Purine

Ribonucleotides

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18
Q

De novo biosynthesis of purines begins with:

A

PRPP with glutamine

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19
Q

During de novo biosynthesis of purines, what are synthesized as AMP and GMP?

A

Adenine and guanine

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20
Q

In de novo biosynthesis of purines, the ring builds up following the addition of:

A

3 atoms from glycine

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21
Q

What is the first intermediate with a full purine ring?

A

Inosin monophosphate (IMP) or inosinate

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22
Q

Intermediate needed for Inosinate to adenylosuccinate

A

Adenylosuccinate synthetase

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23
Q

What enzymes are needed for IMP - adenylosuccinate

A

Aspartate and GTP

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24
Q

Intermediate for IMP to XMP (xanthylate)

A

IMP dehydrogenase

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25
Enzymes needed for IMP- XMP
H2O, NAD+
26
To make GMP, inosinate is deoxidized to _______, This then takes on intermediate ________, with enzymes ___ and ______ to GMP
Xanthylate XMP-glutamamine aminotransferase Glen ATP
27
Site of nucleic acid degradation
Gut
28
In the stomach, what denatures nucleic acid?
Low pH
29
What hydrolysis nucleic acids to nucleotides?
Pancreatic nucleases
30
Intestinal mucosal cells derived nucleotides ________ nucleotides to nucleosides
Dephosphorylate
31
______ nucleosidases generate nitrogenous bases
Intestinal
32
Review slide 10 picture
Slide 10
33
Autosomal recessive deficiency that causes a type o f severe combined immunodeficiency (SCID), involving T cell, B cell and natural killer-cell depletion (lymphocytopenia)
Adenosine Deaminase (ADA) deficiency
34
In catabolism of purine, adenosine is deaminated to _______ Then hydrolysis to:
Inosine Hypoxanthine and xanthine
35
In catabolism of purine, guanosine yields ______ via:
Xanthine Hydrolysis and deamination
36
In catabolism of purine, xanthine is oxidized into ______ by:
Uric acid Xanthine oxidase
37
What is a cofactor for xanthine oxidase?
Molybdenum
38
Rare autosomal recessive deficiency that only affects T cells .
Purine nucleoside phosphorylase (PNP) deficiency
39
Problems PNP deficient people have
Recurrent infections and neurodevelopment delay
40
Disorder characterized by uricemia with recurrent attacks of acute arthritic joint inflammation, caused by deposition of mono-sodium irate crystals
Gout
41
In gout, the hyperuricemia results primarily from :
The underexcretion of uric acid
42
Treatment with ______ inhibits xanthine oxidase, resulting in an accumulation of:
Allopurinol Hypoxanthine and xanthine (compounds more soluble that uric acid)
43
What is important for both salvage and de novo synthesis
PRPP
44
What is reused in salvage pathways for purines?
Free bases released in metabolism
45
Adenine reacts with PRPP to form: It is catalyzed by:
Adenine nucleotide AMP Adenine phosphoribosyltransferase
46
Organ especially dependent on salvage pathway
Brain
47
Lack of hypoxanthine-guanine phosphoribosyltransferase leads to:
Lesch-Nyhan syndrome
48
Syndrome that causes neurological impairment, and finger and toe biting behavior
Lesch-Nyhan syndrome
49
Catalyst for hypoxanthine -> IMP
Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)
50
Catalyst for guanine to GMP
Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)
51
CPS I Cellular location: Pathway involved: Source of nitrogen: Regulators:
Mitochondria Urea cycle Ammonia Activator: N-acetyl-glutamate
52
CPS II Cellular location: Pathway involved: Source of nitrogen: Regulators:
Cytosol Pyrimidine synthesis (de novo) Gamma-amide group of glutamine Activator: PRPP Inhibitor: UTP
53
What is the first full ring synthesized in de novo biosynthesis of pyrimidines?
Dihydroorotate
54
Intermediate for Orotate -> Crotidine 5’monophosphate
Orotate phosphotibosyl transferase | Also takes in PRPP here
55
Intermediate for Crotidine 5’-monophosphate ->.Uridine 5’-monophosphate
OMP decorboxylase
56
First Nucleotide formed in de novo biosynthesis of pyrimidines
Uridine 5’-monophosphate
57
Low activity of Orotate phosphoribosyltransferase and/or OMP decarboxylase could result in:
Poor growth, Megoblastic anemia Excretion of large amounts of Orotate in the urine
58
What helps improve anemia and decreased excretion of Orotate?
Administration of uridine
59
Ribonucleotides are precursors to:
Deoxyribonucleotides
60
Activated state of ribonucleotide reductase is:
Deoxidized, with sulfa-hydro containing enzymes
61
What enzymes are needed to oxidize ribonucleotide reductase? What do they do?
Glutaredoxin or thioredoxin Two H atoms are donated by NADPH and Carried by these two.
62
Activator at primary regulatory sites for regulation of ribonucleotides Inhibitor:
ATP dATP
63
Activator of substrate specificity for regulation of ribonucleotides
DATP, Binding of substrates will activate one another
64
Deamniation of ___ or phosphorylation of ____ yields dUTP
DCTP dUDP
65
Dephosphorylation of _____ by _____ yields dUMP
DUPT DUTPase
66
Methylation of dUMP by ______ ______ yields ___
Thymidylate synthase DTMP
67
What is a target for anti cancer drugs?
Thymidylate synthase
68
DTMP is found exclusively found where?
In DNA
69
DUDP -> dUTP needs what ?
Nucleoside diphosphate kinase
70
DUMP -> DTMP need what?
Thymidylate synthase
71
Cancer drugs will block ________ and/or ______
N5,N10-methylene-tetrahydrofolate 7,8 dihydrofolate
72
_______ and _______ are important chemotherapeutic agents
Fluorouracil Methotrexate
73
In cells, fleorouracil is converted to _____, which inhibits _____ ____
FDUMP Thymidylate synthase
74
Methotrexate, a structural analog of ______, inhibits _____ ____
Tetrahydrofolate Dihydrofolate reductase
75
Widespread deficiency in nutritionally poor populations
Folic acid deficiency
76
Folic acid deficiency leads to:
Reduced Thymidylate synthesis
77
Reduced Thymidylate synthesis causes:
Uracil to be incorporated into DNA
78
In catabolism and salvage of pyrimidines, the ring is:
Open
79
Catabolism and salvage of pyrimidines- CMP and UMP degrade to: TMP degrades to: Final end products:
Beta-alanine Beta-aminosobutyrate NH3/Urea and CO2
80
Painful joints (often in toes) due to deposits of sodium urate crystals
Gout
81
Does gout primarily effect males or females?
Males
82
Gout may involve genetic under-excretion of ______, and/or over-consumption of _____
Urate Fructose
83
How is gout treated?
With avoidance of purine-rich foods (seafood, liver) Or avoidance of fructose Or with xanthine oxidase inhibitor allopurinol
84
Allopurinal can also be used to treat: Why?
Sleeping sickness (trypanosomiasis) Trypanosomes lack enzymes for de novo nucleotide synthesis
85
Trimethoprim can inhibit _____ ____ ____, but binds:
Bacterial Dihydrofolate Human enzyme several orders of magnitude less strongly
86
Principle electron reduction for ribonucleotide reductase
NADPH

Biochemistry II (7 decks)

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