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Biochem BLOCK 3 > Younger Review > Flashcards

Younger Review Flashcards

1
Q

What does PRPP synthetase make?

A

PRPP

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2
Q

Where does the ribose-5P come from?

A

HMP shunt, it then makes PRPP

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3
Q

What does PRPP amidotransferae make?

A

PRNH2

Takes PRPP and makes PRNH2 out of it

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4
Q

What is the regulated committed step in Purine synthesis?

A

PRPP amidotransferase

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5
Q

What are the two enzymes of purine synthesis

A

PRPP synthetase and PRPP amidotransferase

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6
Q

What are the two possible fates of PRPP?

A

Go into purine synthesis or it can have a pyrimidine base added onto it

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7
Q

What is the regulated committed step for pyrimidine synthesis

A

CPS II

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8
Q

What does CPS II do?

A

Starts making the pyrimidine base

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9
Q

What is a positive regulator for PRPP synthetase?

A

Inorganic phosphate

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10
Q

Methotrexate

A
  • folic acid analog
  • an anti tumor drug that inhibits dihydrofolate reductase
  • no DHF to THF, no dTMP
  • can’t make DNA
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11
Q

Trimethoprim

A
  • same as methorexate but works on prokaryotes. Inhibits prokaryotic dihydrofolate reductase
  • antibiotic, prok cant make DNA
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12
Q

Sulfonamides

A
  • structural analog of PABA
  • antibiotic
  • competitive inhibit of bacterial production of folic acid
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13
Q

6-mercaptopurine

A
  • purine analog

- inhibits PRPP amidotransferase

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14
Q

Hydroxyurea

A
  • anti tumor drug that’s inhibits ribonucleotide reductase
  • blocks ribonucleotide conversion into deoxyribonucleotide
  • can treat sickle cell too
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15
Q

5-Fluorouracil

A
  • antitumor drug
  • inhibits thymidilate synthase
  • no methylation of dUMP, so no dTMP
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16
Q

Folate

A

Derivatives are used as carbon donors, methyl groups

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17
Q

What is adenosine deaminase important for?

A

AMP catabolism

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18
Q

Adenosine deaminase deficiency

A
  • Affects T and B cells

- SCID

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19
Q

Treatment for adenosine deaminase deficiency

A
  • bubble
  • bone marrow transplant
  • landmark treatment with gene therapy
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20
Q

Xanthine oxidase

A

Converts purine excretion pathway intermediate (xanthine) to uric acid

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21
Q

Xanthine oxidase deficiency

A
  • Overproduction of uric acid
  • hyperuricemia
  • gout
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22
Q

How do you treat xanthine oxidase deficiency?

A

Allopurinol

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23
Q

Slight deficiency of HGPRT

A

Purine deficiencies

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24
Q

Severe deficiency in HGPRT

A

Forces salvage purines to be excreted

100% excretion as uric acid accumulates dramatically causing Lesch-Nyah’s syndrome

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25
Q

How are nucleotides linked together in nucleic acids?

A

Phosphodiester bonds

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26
Q

How do nucleus acid strands associate with each other?

A

Antiparallel via base pairing using hydrogen bonds

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27
Q

What are the purines?

A

Adenosine

Guanine

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28
Q

What are the pyrimidines

A

Thymine
Uracil
Cytosine

29
Q

How many bonds in GC paring?

A

3 hydrogen bonds

30
Q

How many bonds in AT/AU bonds?

A

2 hydrogen bonds

31
Q

DsDNA with a high GC content

A

Requires higher melting temp

32
Q

DsDNA with high AT content requires

A

Lower melting temp

33
Q

Chargaffs rule

A

A%=T%, C%=G%, A%+T%+G%+C%=100%

34
Q

DNA gyrase

A
  • prokaryote replication
  • topo II
  • cuts both strands to INTRODUCE supercoils and separate linked replicated DNA
35
Q

What inhibits DNA gyrase?

A

Antibiotic quinolones

36
Q

Semiconservative DNA replication

A

1 parent strand

1 new strand

37
Q

Origin of replication in prokaryotes

A

1 origin of replication

38
Q

Origin of replication in eukaryotes

A

Multiple sites

High AT content, easy to melt

39
Q

Bi directional replication

A

Run in opposite directions with replication fork

40
Q

Replication fork

A

Area where DNA helicase opens the two strands

41
Q

single stranded binding proteins (SSBs)

A

Prevent reannealing

42
Q

Topoisomerase I

A
  • nick in 1 strand

- receive supercoiling

43
Q

Topoisomerase II

A
  • nick in 2 strands

- receive supercoiling

44
Q

What direction is DNA polymerized?

A

5’-3’

Requires RNA primer

45
Q

Leading strand

A

-produced continuously 5’-3’

46
Q

Lagging strand

A
  • discontinuous production

- okazaki fragments

47
Q

Okazaki fragments

A

Short stretches of replicated DNA formed as the replication fork moves upstream of the origin of replication for that strand
5’-3’

48
Q

Primase

A

Adds rNTPs to form a primer and 3’-OH site for DNA polymerase activity

49
Q

Primase in eukaryotes

A

Is part of DNA polymerase

50
Q

DNA ligase

A

Seals all the nicks, form phosphodiester bonds

51
Q

Telomeres/telomerase

A

Telomerase is a reverse transcriptase that extends the ends of eukaryotic DNA using RNA as a template to function as a DNA polymerase

52
Q

What is the disease associated with strand directed mismatch repair?

A

HNPCC (hereditary nonpoltposis colorectal cancer)

-terminally differentiated cell starts having telomerase activity

53
Q

Cause and DNA defect associated with xeroderma pigmentosum

A

Thiamine diner causes by UV light

  • cant fix damage
  • Cant repair thiamine dimers
54
Q

DNA replication overview

A
  • initial strand separation (high AT content)
  • SSB proteins prevent reannealing
  • helicase unwinds DNA at the replication fork
  • topoisomerase relieves supercoiling ahead of fork
  • leading strand synthesized continuously
  • lagging strand synthesized discontinuously
  • primase lays down an RNA primer to being each new strand
  • Pol III extends the leading and lagging strand
  • Pol I removes RNA primers and replaces them with DNA
  • DNA ligase seals the nick in the strands
55
Q

Transcription: sigma factor

A

Recognizes promoter sequence in prokaryotic RNA polymerase

56
Q

Transcription: core enzyme

A

Gets recruited and does transcription

57
Q

What is sigma factor + core enzyme?

A

Holoenzyme

58
Q

Rifampin

A

Binds and inhibits core enzyme

59
Q

Prokaryotic promoter sequences

A

-35

TATA(pribnow)

60
Q

Eukaryotic promoter sequence

A

CAT

TATA (hogness)

61
Q

Shine dalgarno sequence

A

Start site for translation in prokaryotes. Polycistronic

62
Q

Polycistronic mRNA

A

Specific to prokaryotes

63
Q

What are the two ways that translation terminates in prokaryotes

A

-rho dependent
-Rho independent
GC stem loop, poly U tail

64
Q

Systemic lupus erythmatosus

A

-dsDNA and snRNPs are identified by the adaptive immune system, young females, weakness and joint pain, butterfly rash

65
Q

Alpha amantin

A
  • toxin from the death cap mushroom causes 95% of mushroom fatalities
  • toxin functions by binding RNA polymerase II and inhibits transcription/ mRNA synthesis in eukaryotes
66
Q

Start codon

A

AUG

67
Q

Stop codons

A

UGA, UAA, UAG

68
Q

Ribosomes translating secretory proteins

A

Are targeted to the ER where they continue to translate the protein into the ER.
-hydrophobic peptide signal emerging from the ribosome plays a role in this

69
Q

Aminoacyl-tRNA synthetase

A
  • decoder
  • recognize codon
  • attach AA to tRNA

Biochem BLOCK 3 (12 decks)

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