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Flashcards in molecular biochem Deck (50):
1

histones

rich in lysine and arginine
positive charge for neg DNA to wrap around
Methylation -> mute
acetylation -> active

2

heterochromatin

HeterChromatin = Highly Condensed
Barr bodies (inactivated X)
Darker on EM

3

Euchromatine

Eu = true = truly transcribed
light on EM

4

Pyrimadines

C-U-T the py

5

purines

pure As Gold

6

which nucleotide has a mehtyl

Thymine

7

which nucleotide bond is stronger

G-C

8

which aa are necessary fro purine synthesis?

GAG
glycine
aspartate
glutamine

9

NucleoSide

base + deoxyribose (Sugar)

10

NucleoTide

nucleoside + phosphaTe

11

leflunomide

inhibits dihydroorotate dehydrogenase
cannot make ortic acid from carbamoyl phosphate and aspartate
therefore cannot make pyrimadines

12

mycophenolate and ribavirin

inhibit IMP dehydrogenase
cannot make GMP from IMP

13

hydroxyurea

inhibits ribonucloside reductase
cannot make dUMP from UDP
therefore cannot make dTMP

14

5-FU

inhibits thymidylate synthase
cannot make dTMP

15

which drugs inhibits Dihydrofolate reductase

MTX
TMP
pyrimethamine
cannot regenerate THF therefore cannot make dTMP

16

what step of nucleotide synthesis is imparied in ortic aciduria?

cannot combine ortic acid w/aspartate to make UMP
cannot make pyrimidines

17

adenosine deaminase deficiency

excess ATP and dATP -> feedback inhibition of DNA synthesis -> decreased lymphocyte counts
major cause of AR SCIDs

18

Lesch-Nyhan syndrome

defective purine salvage d/t absent HGPRT
excess uric acid production and de novo purine synthesis
x-linked recessive
Tx: allopurinol or febuxostat (2nd line)

19

HGPRT acroynm

Hyperuricemia
Gout
Pissed off (aggressive, self-mutilation)
Retardation
dysTonia

20

allopurinol and febuoxostat

xanthine oxidase inhibitors cannot make uric acid

21

probenecid

increases excretion of uric acid in urine

22

DNA topoisomerase

create a single or double stranded break in helix to add or remover super coils
type II/DNA gyrase and type IV inhibited by fluoroquinolones

23

DNA polymerase III

prokaryotic only
elongates laggin strand until it reaches primer of preceding fragments
5'-3' synthesis
3'-5' proof reading

24

DNA polymerase I

prokaryotic only
degrades DNA primer and replaces it with DNA
same as III, but ecises RNA primers w/5'-3' exonuclease

25

telomerase

RNA-dependent DNA polymerase that adds DNA to 3' end of chormosomes to avoid loss of genetic material w/duplication
Eukaryotes only

26

Lac operon

E. coli, increases lactose metabolism when needed
low glucose -> increased AC -> increased cAMP -> activation CAP -> increased transcription
high lactose -> unbinds repressor protein -> increased transcription

27

nucleotide excision repair

endoneucleases release oligonucelotides w/damaged bases
repairs bulky helix distorting lesions (UV damage)
G1 phase
defective in xeroderm pigmentosum

28

xeroderma pigmentosum

prevents repair of pyrimidine dimers d/t UV exposure

29

base excision repair

base-specific glycosylase removes altered base
thru-out cell cycle
important in repair of spontaneous/toxic deamination

30

mismatch repair

mismatched nucleotides are removed
G2 phase
defective in hereditary non-polyposis colorectal cancer (HNPCC)

31

nonhomologous end joining

repairs double stranded breaks
some DNA ma be lost
mutated in ataxia telangiectasia and fanconi anemia

32

DNA/RNA/protein synthesis direction

DNA and RNA are both synthesized 5' -> 3'
5' end bares triphosphate (energy for bond)
protein synthesis N->C
mRNA read 5' -> 3'

33

mRNA codones

AUG (inAUGurates synthesis)
rarely GUG
in eukaryotes codes for methionine
in prokaryotes codes for fMet

34

mRNA stop codones

UGA
UAA
UAG

35

promoter sequence

TATA box
RNA polymerase II binds
mutations usually result in dramatic decrease in gene transcription

36

RNA polymerase I

makes rRNA (most numerous/Rampant)

37

RNA polymerase II

makes mRNA (largest/massive)
opens DNA at promoter site

38

RNA polymerase III

makes tRNA (smallest/tiny)

39

RNA polymerases

do not have proof reading ability
prokaryotes have 1 polymerase w/all 3 fnxs

40

alpha-amanitin

found in amansita phalloides (death cap mushrooms)
inhibits RNA polymerase -> severe hepatotoxcity

41

rifampin

inhibits prokaryote RNA polymerase

42

actinomycin D

inhibits RNA polymerases in both prokaryotes and eukaryotes

43

RNA processing in eukaryotes

initial transcript is hnRNA which is modified:
-capping of 5' end
-polyadenylation of 3'
-splicing of introns
-> mRNA -> transported into cyto for translation

44

anti-snRNPs

aka Smith Abs
SLE

45

anti-U1 RNP abs

mixed CT disease

46

tRNA structrue

cloverleaf form
anti-codon end opposite 3/ aminoacyl end
CCA at 3' end (Can Carry Aa)

47

charging of tRNA

aminoacyl-tRNA synthetase checks to make sure matchis correct

48

wobble

accuracy only required for first two base-pairs

49

protein synthesis initiation

initiated by GTP hyrolysis, initiation factors help assemble 40s, released when 60s binds

50

elongation

aminoacyl-tRNA binds to site A
rRNA catalyzes peptide bond
riboseoms advances 3 nucleotides toward 3' end of mRNA