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MCM: Biochem, Exam 1 > Nucleotide metab > Flashcards

Nucleotide metab Flashcards

1
Q

What is used for Purine Nucleotide sythesis that comes from the Pentose Phosphate Pathway?

A

Ribose sugar

Ribose 5-phosphate

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2
Q

NADH generally helps with _____, while NADPH helps with___.

A

breakdown, prod. of TCA, drives ATP, Catabolic processes

bulding things, from pentose phosphate pathway

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3
Q

What enzyme does Methotrexate inhibit?

A

DHFR, in the oxidation of NADPH by DHRF

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4
Q

How does our body balance the amount of Adenine, Thiamine, Guanine, Cytosine?

A

Feeback and Cross reg. during PURINE nucelotide synth.

IMP, AMP, GMP, products of this pathway, INHIBIT the main guy PRPP’s synth.

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5
Q

Phases of Pyrimidine Nucl. synth?

A

Phase 1: fabricate orotate ring
Phase 2: Attach PRPP to form UMP
Phase III: Convert UMP to uridine, cytosine, thymidine (doexy)nuleotides

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6
Q

Phases in Purine Synthesis?

A
  1. Ribose-5P activation (which comes from PPP)
  2. Convert PRPP to PRA
    * *3. Construct IMP ring
    * *4. Convert IMP to adenosine and guanosine (doxy)nucleotides
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7
Q

Acyclovir

A

terminates DNA replication (lacks 3’-OH group, terminator)
treats sores for Herpes, Chicken pox
Thymidine kinase has more affinity for acyclovir

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8
Q

_____ + _____ = Uric Acid

A

GMP + AMP eventually in PURINE nucl. catabolism make Uric Acid

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9
Q

What molecule is inhibited to help with gout pts? What enzymes does this affect?

A

Allopurinol, which affects xanthine oxidase, lowering teh number of xanthine to Uric Acid.

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10
Q

Why does uric acid, but not it’s intermediates before it during Nucl. catabolism cause gout?

A

It has 3 oxygens

less water soluble (incr. solubility in joint)

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11
Q

three endproducts of pyrimidine nucl. catabolism?

A

Malonyl CoA, ketogenic

**Beta-aminoisobutyrate (from dTDP and dTTP) make
methylmalonyl CoA
Succinyl CoA
both glucogenic

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12
Q

sources of atoms in Purine bases

A

CO2, Gln, Gly, Asp, N10-formyl THF

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13
Q

pyrimidine atom sources

A

HCO3-, Gln, Asp, N5-methylene THF

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14
Q

What comes before ATP, GTP (RNA) and dATP, dGTP(DNA) during purein ring synth?

A

IMP

It is converted to AMP or GMP

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15
Q

Commited step in purine synthesis?

A
  • fomration of phosphoribosyl amine
    glutamine: phosphoribosyl pyrophosphate amidotransferase

pushed forward from PRPP, the molecule jus the step before via positive feedforward

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16
Q

During what stage of ____ synthesis does Methotrexate attack?
What vitamin does it look very similar to?

A

Phase III: IMP ring contstruction
Purine ring

B9, folic acid. Competative inhibitor for enzymes taht use folate

17
Q

Methotrexate prevents ____ of NADPH by ___.

A

oxidation

DHFR

18
Q

Sulfa drugs work by___.

A

Being a competative inhibitor for PABA, the intermeidate for folate synth.

19
Q

PRPP is inhibited on both sides by ___, the end products of purine nucleotides.

A

IMP, AMP, GMP

Accumulation of its own endproducts inhibits its own synth.

20
Q

How are the number of Gs and As balanced?

A

In Purine synth, AMP synth. stimulated by GTP, and vise versa GMP synth is stimulated by ATP, to ensure they’re balanced and made enough equally

21
Q

Salvage pathway enzymes

A

HGPRT

APRT

22
Q

Commited step of pyrimidine synth

A

Carbamoyl Phosphate Synthase II

The first step

23
Q

What phase does the anticancer drug 5-fluorouracil (Adrucil) work?

A

phase 3: convert UMP to uridine, cytosine, thymidine deoxynucleoties

Blocks** thymidylate synthase* which stops DNA production in cancer

24
Q

**two regulatory points of pyrimidine synthesis

A
  1. carbamoyl phosphate synthetates
    inh. by UMP and Purines(end product), stim. by PRPP(
  2. Aspartate transcarbamoylase (ATCase)
    Feedback inh. by CTP (endproduct)
25
Q

Ortic Aciduria is an issue in what phase of pyrmidine synth?

A

Phase 2: attach PRPP to form UMP
Issue with UMP Synthase
Buld up of Oric acid in urine, it cant be converted to UMP

26
Q

Acyclovir works by resembling a guanine analogue that the virus has a higher affinity for. what happens then?

A

it’s helps treat herpes and chicken pox cores bc. DNA polymerase cannot use the DNA bc its a fake nucelotide
Viral supression

27
Q

Purine synth happens in the ____ while pyrimidine synth happens in the ____.

A

cytosol

cytosol and mitochondira

28
Q

enzymes needed for nucleotide degradtion

A

“Racing Phor New Nuceotides”

  1. ribonucleases and deoxyribnucleases (conver RNA/DNA to short oligomers
  2. Phosphodiesterases: convert short oligomers to NMPs or dNMPs
  3. Nucleotidases: NMPs/dNMPs to nucleosides and deoxynucleosides
  4. Nucleosidases: remove ribose gorup, conver to pyrimidiens, purines
29
Q

AMP and GMP break down to __

A

Uric Acid

30
Q

Allopurinol inhibits Hypoxanthine and xanthine from turning into Uric acid. These two molecules build up, yet the drug helps with Gout. How?

A

Uric Acid has 3 oxygens making it less water soluble, more gout causing.
Xanthine 2, and hypoxanthine have only 1 Oxygens and are more water soluble
Monosodium Urate (MSU) crystals
“disease of the wealthy” from wine and protein rich food

31
Q

AMP to IMP to Inosine to ___ to Xanthine to ___

A

hypoxanthine

uric acid

32
Q

ADA deaminase does what? what happens if its too much or too little?

A

adenosine homeostatis, breaks down adenosine form food
too much: hemolytic anemai, premature destruction of RBC
too little: SCID, severe combined immunodeficiency

33
Q

End products of pyrimidine catabolism?

A

malonyl CoA
MEthylmalonyl CoA
Succinyl CoA

34
Q

Pyrimidine salvage pathyway step taht acyclovir inhibits?

A

thymidine kinase, not dTMP production

35
Q

PRPP =

A

phospho ribosyl pyrophosphate

36
Q

Lesch Nyhan syndrom is from a default in the ___ enzyme in the ___ salvage pathway.

A

HGPRT
Purine
overproduction of uric acid

37
Q

Committed step in purinidine synth?

A

First step,

Carbamoyl phosphate synthetade II

38
Q

Anti cancer for pyrimidine synth?

A

Adrucil
Aka 5-Fluorouracil

Stops dna production

MCM: Biochem, Exam 1 (5 decks)

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