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Molecular Medicine > Nucleotide Synthesis And Metabolism > Flashcards

Nucleotide Synthesis And Metabolism Flashcards

1
Q

What are the components of a nucleotide

A

Phosphate group
Nitrogenous Base
Ribose or pentose

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2
Q

What are the components of a nucleoside

A

Nitrogenous Base

Ribose / Pentose sugar

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3
Q

What are the different Purines

A

Adenine, Guanine

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4
Q

What are the different Pyrimidines

A

Uracil, Thymine, Cytosine

CUT

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5
Q

Which nitrogen base has 2 ring structures

A

Adenine
Guanine
(Purine)

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6
Q

Which nitrogenous base has 1 ring structure

A

Cytosine
Thymine
Uracil

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7
Q

True or false, thymine is found in RNA

A

False, it is found in DNA

Uracil is found in RNA

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8
Q

What suffix is added to nucleoside s when they become nucleotide

A

-ylate

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9
Q

What is Chargraffs rule

A 
A%= T%
G%= C%

I.e purines = pyrimidines

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10
Q

In complementary base pairing, which pair has
I) double bonds
II) triple bonds

A

A-T

G-C

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11
Q

True or False, DNA structures are parallel

A

False, they are anti parallel

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12
Q

What are the two Anti- tumor drugs involved in disrupting the DNA structure, used mainly for patients with Leukemia

A

Daunorubicin

Doxorubicin

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13
Q

How does Daunorubicin and Doxorubicin disrupts the DNA structure

A

Intercalates between the bases of DNA, preventing proper replication of DNA

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14
Q

What drug is used in treating bladder and lung tumors

A

Cisplatin

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15
Q

How does Cisplatin disrupt DNA replication

A

Distorts and Malfunction of DNA

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16
Q

What are histones predominantly made from

A

Arginine and lysine

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17
Q

What are the components of chromatin

A

DNA, Histone

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18
Q

What are the two types of pathways for nucleotide Synthesis

A

De novo

Salvage Pathway

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19
Q

What are the metabolic precursors in de novo Synthesis

A

Amino Acids
Ribose 5- phosphate
CO2
NH3

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20
Q

What is the pyrimidine ring synthesized as

A

Orotate

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21
Q

In which pathway do the free bases act as intemediates

A

Salvage Pathway

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22
Q

What are the shared precursors in the de novo pathway of pyrimidine and purine

A

PRPP (phospho-robosyl-pyrophosphate)

23
Q

What are the sources of amino groups

A

Glutamine

Aspartate

24
Q

Describe the steps involve in the De novo synthesis of Purines
(Please include enzymes and what inhibits each step)

A

(Insert picture)

25
Q

What enzymes are involved in the salvage pathway of purine bases

A
  1. Adenine phosphoribosyltransferse

2. Hypoxanthine- Guaninephosphoribosyltransferase (HGPRT)

26
Q

Which pathway uses less energy

A

Salvage pathway

27
Q

True or False, Salvage Pathway of Purine Bases are irreversible

A

True

28
Q

Describe the steps involved in the salvage pathway of purines

(Please include enzyme used)

A

(Insert Picture here)

29
Q

Describe the steps involved in the degradation of Purines

A

(Insert Picture here )

30
Q

What enzyme deficiency is present in SCID

A

Adenosine Deaminase

31
Q

What 2 molecules can adenosine be converted to when ADA isn’t present

A

dATP and ribonucleotide

32
Q

How does ADA deficiency cause SCID

A

(Insert picture here)

33
Q

What two methods can be used to cure SCID

A
  1. Bone Marrow Replacement Therapy (human leukocyte antigen HLA)
    2, Enzyme Replacment Therapy
    Synthetic ADA administered in complex with PEG (polyethylene glycol) ADA-PEG
34
Q

Hyperurciemia and Gout May accompany which conditions

A

(Insert Picture Here)

35
Q

What drug is used to inhibit xanthine oxidase for the treatment of Gout

A

Allopurinol

36
Q

What does xanthine oxidase convert allopurinol into

A

Oxypurinol (alloxanthine)

37
Q

What two drugs are used in the treatment of acute attacks of gout

A

Colchicine, Indomethacin

38
Q

What drug is used for chronic hyperuricemia caused by underexcretion of Uric acid

A

Probenecid

39
Q

Lesch- Nyhan Syndrome is due to a near complete deficiency of what enzyme

A

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)

40
Q

What are the symptoms of Lesch Nyhan Syndrome

A

Mental Retardation
Compulsive destructive behavior (biting of hands and lips)
Involuntary movements
Heritable cause of hyperuricemia
Death often in first decade (renal failure)

41
Q

What is used in the treatment of Lesch-Nyhan Syndrome

A

Allopurinol

42
Q

In pyrimidine de novo synthesis,
________ acts as an C and N donor
________ acts as a N donor
________ acts as a carbon donor

A

Aspartate
Glutamine
CO2

43
Q

What are the symptoms of Hereditary Orotic Aciduria

A

Severe Anemia
Growth retardation
High Levels of Orotic Acid Excretion

44
Q

What is the major regulatory step in making Orotate in pyrimidine biosynthesis

A

Carbomyl Phosphate Synthase II

45
Q

How does ingesting Uridine treat Hereditary Orotic Aciduria

A
  1. Uridine is broken down into UMP by the enzyme uridine phosphorylase in the salvage pathway
  2. UMP is converted into UDP and UTP
  3. UTP inhibits the enzyme carbomyl phosphate synthase II through a negative feedback mechanism
  4. This enzyme is a major regulatory step in the production of orotate thereby decreasing Orotic Acid levels
46
Q

What is the biochemical basis of Hereditary Orotic Aciduria

A

Defect in one or both activities of

  1. Orotate phosphoribosyl transferase
  2. Oritidine Decarboxylase
  3. Separate catalytic domain of the enzyme UMP synthase
47
Q

What is the chemical reaction for the salvage pathway of pyrimidine bases
(Please include enzyme )

A

(Insert Picture here )

48
Q

What enzyme is used in the conversion of ribonucleotides to deoxyribonucleotides

A

Ribonucleotide reductase

49
Q

Describe the steps involved in the formation of dTMP

A

It involves the the methylation of D-uridylate
The methyl group is from the compound N- Methylenetetrahydrofolate
With the use of the enzyme thymidylate synthase that catalyses the reaction
Tetrahydrofolate must be federated in order for this reaction to occur

50
Q

Describe the steps involved in the regeneration of tetrahydrofolate (include enzyme)

A

Synthesis of dihydrofolate from the formation of dTMP

Dihyrofolate + NADPH(reducing agent) + dihyrdofolate reductase (enzyme)

51
Q

Describe the steps involved in the degradation of TMP

A

(Inserts Picture here)

52
Q

Describe the steps involved in the degradation of CMP

A

(Insert Picture here)

53
Q

What compound which is excreted in urine is produced at increased levels during chemo and radiation for cancer patients

A

B - aminoisobutyric acid

Molecular Medicine (1 decks)

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