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B&B Biochemistry Flashcards

1
Q

Located in nucleus of eukaryotic cells

-Contains genetic code

A

DNA

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2
Q

Located in cytoplasm of prokaryotic cells

A

DNA

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3
Q

The DNA structure is composed of

A

Sugar (ribose) backbone, Nitrogenous base, phosphate

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4
Q

Made up of a pentose sugar, nitrogenous base, and phosphate group

A

Nucleotide

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5
Q

What if the difference between nucleotides and nucleosides?

A

Nucleotides have a phosphate group

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6
Q

Synthesized as monophosphates and then converted to triphosphate form

A

Nucleotides

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7
Q

Occurs in segments with GC patterns (GC Islands)

A

DNA methylation

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8
Q

Inactivates transcription

A

DNA Methylation

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9
Q

Unmethylated GC stimulates an

A

Immune Response

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10
Q

Bacteria methylate

A

Cytosine and adenine

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11
Q

Methylation protects bacteria from

A

Viruses (phages)

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12
Q

In bacteria, non-methylated DNA is destroyed by

A

Endonucleases

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13
Q

Found in nucleus of eukaryotic cells

-DNA plus proteins

A

Chromatin

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14
Q

Units of histones plus DNA

A

Nucleosome

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15
Q

Histones contain basic amino acids with high content of

A

Lysine and arginine

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16
Q

Positively charged and binds to the negatively charged phosphate backbone

A

Histones

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17
Q

Distinct from other Histones because it is not in the nucleosome core.

-Larger and more basic

A

H1

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18
Q

Fever, joint pains, and rash after starting a drug

A

Drug-induced lupus

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19
Q

Caused by anti-histone antibodies in 95% of cases

A

Drug-induced lupus

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20
Q

Classic lupus is caused by

A

anti-dsDNA

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21
Q

What are the three classic drugs that cause drug-induced Lupus?

A

Hydralazine, Procainamide, and Isoniazid

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22
Q

Condensed chromatin where DNA sequences are not transcribed

-Significant DNA methylation

A

Heterochromatin

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23
Q

Less condensed form of chromatin

-Transcriptively active

A

Euchromatin

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24
Q

In heterochromatin, we see significant

A

DNA methylation

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25
Q

In euchromatin, we see significant

A

Histone Acetylation

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26
Q

Acyl group is added to lysine, which relaxes the chromatin for transcription

A

Histone acetylation

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27
Q

We see increased expression of some histone deacetylases in some

A

Tumors

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28
Q

What are two things that histone deacetylase inhibitors are used for?

A

Anti-cancer and Huntington’s

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29
Q

A possible mechanism for Huntington’s disease is

A

Histone Deacetylation

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30
Q

cAMP levels mediate

A

Blood flow

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31
Q

cGMP often serves as a

A

Secondary messenger

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32
Q

RNA is synthesized first and then is later converted to

A

DNA

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33
Q

The goal of purine synthesis is to create

A

AMP and GMP

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34
Q

Step 1 of purine synthesis is to create

35
Q

Then, step 2 of purine synthesis is to create

36
Q

What are the three nitrogen sources from purine synthesis?

A

Aspartate, Glycine, and Glutamate

37
Q

What are the three carbon sources during purine synthesis?

A

CO2, Glycine, and Tetrahydrofolate

38
Q

A major contributor to the formation of purines is

39
Q

IMP is then used to create

A

AMP and GMP

40
Q

Purine synthesis starts with ribose phosphate from the

41
Q

Converts ribonucleotides to deoxyribonucleotides

A

Ribonucleotide Reductase

42
Q

Inhibits IMP dehydrogenase

-Blocks the conversion of IMP to GMP

43
Q

Ribavirin inhibits the synthesis of

A

Guanine nucleotides (purines)

44
Q

An immunosuppressant that inhibits IMP dehydrogenase

A

Mycophenolate

45
Q

Slavages the bases adenine guanine, and hypoxanthine

A

Purine Salvage

46
Q

Purine salvage requires

47
Q

In the purine salvage pathway, hypoxanthine and guanine are converted to IMP and GMP respectively by

48
Q

In the purine salvage pathway, adenine is converted to AMP by

A

APRT (Adenine phosphoribosyl transferase)

49
Q

A chemotherapy agent that mimics hypoxanthine and guanine

A

6-Mercaptopurine

50
Q

Added to PRPP by HGPRT to create Thioinosinic acid

A

6-Mercaptopurine

51
Q

The overall effect of 6-Mercaptopurine is a decrease in

A

IMP, AMP, and GMP

52
Q

An immunosuppressant that is converted to 6-MP

A

Azathioprine

53
Q

In the purine breakdown pathway, hypoxanthine is converted to Xanthine by

A

Xanthine Oxidase

54
Q

In the purine breakdown pathway, Guanine is converted to Xanthine by

55
Q

Then, Xanthine (from hypoxanthine and guanine) is converted to uric acid by

A

Xanthine oxidase

56
Q

Crystal deposition in joints caused by excess uric acid

57
Q

Can occur from high cell turnover (trauma or chemo) and consumption of purine-rich foods like meat and seafood

58
Q

The treatment for gout is

A

Xanthine oxidase inhibitor (Allopurinol)

59
Q

Azathioprine and 6-MP are metabolized by

A

Xanthine oxidase

60
Q

May boost effects of 6-MP and increase toxicity of the drug

A

Co-treatment with allopurinol

61
Q

X-linked absence of HGPRT

-results in excess uric acid production

A

Lesch-Nyhan Syndrome

62
Q

In Lesch-Nyhan syndrome, we see excess denovo purine synthesis, which means increases in

A

PRPP and IMP

63
Q

The classic presenting feature of Lesch-Nyhan Syndrome is

A

Self-mutilating behavior

64
Q

A male child with motor symptoms, self mutilation, and gout, is the classic presentation of

A

Lesch-Nyhan Syndrome

65
Q

The goal of pyrimidine synthesis is to create

A

CMP, UMP, and TMP

66
Q

Step one of pyrimidine synthesis is to make

A

Carbamoyl phosphate

67
Q

In step one of pyrimidine synthesis, it is important to note that

A

Ring is formed first, then ribose is added

68
Q

Step 2 of pyrimidine synthesis is to make

A

Orotic Acid

69
Q

Step 3 of pyrimidine synthesis is to make

70
Q

Orotic acid and PRPP are combined to make UMP by

A

UMP synthase

71
Q

The key point of pyrimidine synthesis is that UMP is synthesized first and the from UMP we derive

A

CMP and TMP

72
Q

The pryimidine ring is made up of

A

2 Nitrogens and 4 Carbons

73
Q

3 carbons and 1 nitrogen of the pyrimidine ring are derived from

74
Q

1 nitrogen and 1 carbon of the pyrimidine ring are derived from

A

Carbamoyl Phosphate

75
Q

Autosomal recessive disorder caused by a defect in UMP Synthase

A

Orotic Aciduria

76
Q

Orotic aciduria is characterized by a loss of pyrimidines and a buildup or

A

Orotic Acid

77
Q

What are 3 key findings of Orotic Aciduria?

A
  1. ) Orotic acid
  2. ) Megaloblastic Anemia
  3. ) No B12/Folate response
  4. ) Growth Retardation
78
Q

How do we treat Orotic Aciduria and what is the effect of this treatment?

A

Treat with Uridine

-Bypasses UMP synthase

79
Q

Key urea cycle enzyme, which functions to combine carbamoyl phosphate with ornithine

A

Ornithine TransCarbamoylase (OTC)

80
Q

OTC combines carbamoyl phosphate w/ ornithine to make

A

Citrulline

81
Q

OTC deficiency results in increased carbamoyl phosphate which causes increases in

A

Orotic Acid

82
Q

We want to be careful not to confuse OTC deficiency with

A

Orotic aciduria

83
Q

How do we distinguish between OTC deficiency and orotic aciduria?

A

OTC has increased ammonia levels

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