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Biochemistry > MCM - Nucleotide Metabolism > Flashcards

MCM - Nucleotide Metabolism Flashcards

1
Q

Nucleosides vs. Nucleotides

A

Nucleosides have a Base and a Sugar

Nucleotides have: Base, Sugar, and Phosphate

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2
Q

How is Adenine bonded with the Ribose Sugar

A

Via a Glycosidic Bond

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3
Q

How many Carbons does a Purine have in its ring

A

9

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4
Q

How many carbons does a Pyrmadine have in its carbon ring

A

6

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5
Q

Which bases are in DNA

A

Adenine
Guanine
Cytosine
Thymine

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6
Q

Which bases appear in RNA

A

Guanosine
Uracil
Adenine
Cytosine

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7
Q

What are some other roles of Nucleosides and Nucleotides

A

ATP & GTP

Cosubstrates

Components of Co-Factors
CoA
FAD
FMN
UDP-Glc
NAD+
NADP+

Regulatory Role
cAMP
gAMP
m7GTP

Important Biomolecules;
Vitamin B12

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8
Q

Are the carbon sources for Purine and Pyrmadine Ring formation the same

A

No

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9
Q

Purine Synthesis Basic Steps

A

Sugar Molecule Synthesis

AND THEN

Ring Formation

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10
Q

Pyrmadine Synthesis Basic Steps

A

Ring Formation

AND THEN

Sugar Formation

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11
Q

How many phases of De Novo Synthesis does it take to make a Purine

A

4 stages

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12
Q

What are the 4 stages of the De Novo Synthesis for Purine Formation

A
  1. Ribose-5-P Activation; phosphorylation of Ribose-5-P to Phospho-Ribosyl-Pyro-Phosphate (PRPP)
  2. Conversion of PRPP to Phosphoribosylamine (PRA); the rate limiting step of the De Novo Synthesis of Purines
  3. Conversion of PRA to an Inosine Monophosphate (IMP) (Ring)
  4. Conversion of IMP to Adenosine or Guanosine
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13
Q

What does Methotrexate inhibit in the De Novo Synthesis

A

The synthesis of the IMP ring for Purine Synthesis

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14
Q

What is IMP converted to

A

Guanosine
or
Adenosine;

Depending on GMP/AMP Levels

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15
Q

Sulfa drugs effect on Folate

A

Inhibit the Bacterial DHPS and DHFR; so the bacterial, viral, or fungal cells cannot make folate from PABA

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16
Q

What is the feedback inhibition on the De Novo Synthesis of Purines

A

Accumulation of PRPP
Accumulation of PRA
Accumulation of GMP/AMP

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17
Q

What is the rate limiting step in the synthesis of Pyrmidine Ring

A

Carbamoyl Phosphate + Aspartate —>
Carbamoylaspartate

Enzyme: Aspartate Transcarbamoylase

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18
Q

How many Steps is the Synthesis of a Pyrmidine

A

3 Steps

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19
Q

What are the Steps of synthesizing a Pyrmidine Ring

A
  1. Fabrication of orotate ring
  2. Attachment of PRPP to form UMP
  3. Convert UMP to uridine, cytosine, and thymidine
20
Q

What are the two major regulatory steps in Pyrmidine Synthesis

A

Carbamoyl Phosphate Synthetase

And

Aspartate Transcarbamoylase

21
Q

What inhibit Carbamoyl Phosphate Synthetase

A

UMP
And
Purines

22
Q

What Stimulates Carbamoyl Phosphate Synthetase

A

PRPP

23
Q

What does CTP Inhibit via Feedback Inhibition

A

Aspartate Transcarbamoylase

24
Q

What is the cancer drug for Pyrmidine Synthesis

A

Adrucil
(5-Fluorouracil)

Mechanism not clear; likely inhibits Thymidylate Synthase

25
Q

What are the two defective enzymes in Oroctic Aciduria

A

Orotate phosphoribosyl transferase

and

Oritidine Carboxylase

26
Q

How does Acyclovir work

A

Acts as a Nucleoside; which binds a phosphate

Leads to DNA Polymerase being blocked by a false nucleotide; the name of the kinase that is blocked is Thymidine Kinase, only in virally infected cells

27
Q

What is Acyclovir generally used for

A

Herpes Lesions
and
Chicken Pox

28
Q

Where does Pyrmidine Synthesis Occur

A

In the Cytosol
And
The Mitochondria

29
Q

What do Ribonucleases do

A

Convert RNA to short oligomers

30
Q

What do Deoxyribonucleases do

A

Convert DNA to short oligomers

31
Q

What do Phosphodiesterases do

A

Convert short oligomers to NMP’s or dNMP’s

32
Q

What does a Nucelotidase do

A

Converts dNMP/NMP into nucelosides and deoxynucelosides

33
Q

What do Nucleosidases do

A

Remove Ribose group and converts them into Pyrmidines or Purines

34
Q

What is Uric Acid a product of

A

Purine Nucleotide Catabolism

35
Q

What does a build up of Adenosine Deaminase do

A

Causes hemolytic anemia

36
Q

What does underproduction of Adenosine Deaminase do

A

Associated with the second most common form of sever combined immunodeficiency (SCID)

37
Q

What is Gout caused by

A

A build up of Uric Acid from eating to many high protein foods and drinking too much wine

38
Q

How are Uric Acid Crystal Formed

A

Urate binds with sodium to make Monosodium Urate; which is not water soluble

This precipitates out of solution are forms Uric Acid Crystals

39
Q

What does Pyrmidine Nucleotide Catabolism Produce

A

Malonyl-CoA; Can go into Fatty Acid Synthesis
or
Methylmalonyl-CoA and Succinyl-CoA; Can go into TCA Cycle

40
Q

What is used in the Catabolism of Pyrmidine Nucleotides to determine DNA Turnover

A

ß-Aminoisobutyrate

41
Q

What is the Pyrmidine Nucleotide Salvage Pathway

A

Takes Pyrmidines to their respective -TP molecule

42
Q

What is the Purine Salvage Pathway

A

Takes a Purine into their respective -MP

43
Q

Lesch-Nyhan Syndrome Cause

A

Defect in the HGPRT enzyme in the Purine Salvage Pathway

44
Q

What does the defect in HGPRT Produce in Lesch-Nyhan Syndrome

A

Overproduction of Uric Acid

45
Q

How do patients present with Lesch-Nyhan Syndrome

A

Hyperuricemia and Hyperuricosuria

46
Q

What are the symptoms of Hyperuricemia and Hyperuricsuria

A

Urate Kidney Stones, Poor Muscle Control, Mental Retardation, and tendency FOR SELF MUTILATION

47
Q
A

Biochemistry (7 decks)

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