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Flashcards in Younger Review Deck (69):
1

What does PRPP synthetase make?

PRPP

2

Where does the ribose-5P come from?

HMP shunt, it then makes PRPP

3

What does PRPP amidotransferae make?

PRNH2
Takes PRPP and makes PRNH2 out of it

4

What is the regulated committed step in Purine synthesis?

PRPP amidotransferase

5

What are the two enzymes of purine synthesis

PRPP synthetase and PRPP amidotransferase

6

What are the two possible fates of PRPP?

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

7

What is the regulated committed step for pyrimidine synthesis

CPS II

8

What does CPS II do?

Starts making the pyrimidine base

9

What is a positive regulator for PRPP synthetase?

Inorganic phosphate

10

Methotrexate

-folic acid analog
-an anti tumor drug that inhibits dihydrofolate reductase
-no DHF to THF, no dTMP
-can't make DNA

11

Trimethoprim

-same as methorexate but works on prokaryotes. Inhibits prokaryotic dihydrofolate reductase
-antibiotic, prok cant make DNA

12

Sulfonamides

-structural analog of PABA
-antibiotic
-competitive inhibit of bacterial production of folic acid

13

6-mercaptopurine

-purine analog
-inhibits PRPP amidotransferase

14

Hydroxyurea

-anti tumor drug that's inhibits ribonucleotide reductase
-blocks ribonucleotide conversion into deoxyribonucleotide
-can treat sickle cell too

15

5-Fluorouracil

-antitumor drug
-inhibits thymidilate synthase
-no methylation of dUMP, so no dTMP

16

Folate

Derivatives are used as carbon donors, methyl groups

17

What is adenosine deaminase important for?

AMP catabolism

18

Adenosine deaminase deficiency

-Affects T and B cells
-SCID

19

Treatment for adenosine deaminase deficiency

-bubble
-bone marrow transplant
-landmark treatment with gene therapy

20

Xanthine oxidase

Converts purine excretion pathway intermediate (xanthine) to uric acid

21

Xanthine oxidase deficiency

-Overproduction of uric acid
-hyperuricemia
-gout

22

How do you treat xanthine oxidase deficiency?

Allopurinol

23

Slight deficiency of HGPRT

Purine deficiencies

24

Severe deficiency in HGPRT

Forces salvage purines to be excreted
100% excretion as uric acid accumulates dramatically causing Lesch-Nyah's syndrome

25

How are nucleotides linked together in nucleic acids?

Phosphodiester bonds

26

How do nucleus acid strands associate with each other?

Antiparallel via base pairing using hydrogen bonds

27

What are the purines?

Adenosine
Guanine

28

What are the pyrimidines

Thymine
Uracil
Cytosine

29

How many bonds in GC paring?

3 hydrogen bonds

30

How many bonds in AT/AU bonds?

2 hydrogen bonds

31

DsDNA with a high GC content

Requires higher melting temp

32

DsDNA with high AT content requires

Lower melting temp

33

Chargaffs rule

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

34

DNA gyrase

-prokaryote replication
-topo II
-cuts both strands to INTRODUCE supercoils and separate linked replicated DNA

35

What inhibits DNA gyrase?

Antibiotic quinolones

36

Semiconservative DNA replication

1 parent strand
1 new strand

37

Origin of replication in prokaryotes

1 origin of replication

38

Origin of replication in eukaryotes

Multiple sites
High AT content, easy to melt

39

Bi directional replication

Run in opposite directions with replication fork

40

Replication fork

Area where DNA helicase opens the two strands

41

single stranded binding proteins (SSBs)

Prevent reannealing

42

Topoisomerase I

-nick in 1 strand
-receive supercoiling

43

Topoisomerase II

-nick in 2 strands
-receive supercoiling

44

What direction is DNA polymerized?

5'-3'
Requires RNA primer

45

Leading strand

-produced continuously 5'-3'

46

Lagging strand

-discontinuous production
-okazaki fragments

47

Okazaki fragments

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

48

Primase

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

49

Primase in eukaryotes

Is part of DNA polymerase

50

DNA ligase

Seals all the nicks, form phosphodiester bonds

51

Telomeres/telomerase

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

52

What is the disease associated with strand directed mismatch repair?

HNPCC (hereditary nonpoltposis colorectal cancer)
-terminally differentiated cell starts having telomerase activity

53

Cause and DNA defect associated with xeroderma pigmentosum

Thiamine diner causes by UV light
-cant fix damage
-Cant repair thiamine dimers

54

DNA replication overview

-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

Transcription: sigma factor

Recognizes promoter sequence in prokaryotic RNA polymerase

56

Transcription: core enzyme

Gets recruited and does transcription

57

What is sigma factor + core enzyme?

Holoenzyme

58

Rifampin

Binds and inhibits core enzyme

59

Prokaryotic promoter sequences

-35
TATA(pribnow)

60

Eukaryotic promoter sequence

CAT
TATA (hogness)

61

Shine dalgarno sequence

Start site for translation in prokaryotes. Polycistronic

62

Polycistronic mRNA

Specific to prokaryotes

63

What are the two ways that translation terminates in prokaryotes

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

64

Systemic lupus erythmatosus

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

65

Alpha amantin

-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

Start codon

AUG

67

Stop codons

UGA, UAA, UAG

68

Ribosomes translating secretory proteins

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

Aminoacyl-tRNA synthetase

-decoder
-recognize codon
-attach AA to tRNA