molecular biochem

Question 1

histones

Answer 1

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

Question 2

heterochromatin

Answer 2

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

Question 3

Euchromatine

Answer 3

Eu = true = truly transcribed

light on EM

Question 4

Pyrimadines

Answer 4

C-U-T the py

Question 5

purines

Answer 5

pure As Gold

Question 6

which nucleotide has a mehtyl

Answer 6

Thymine

Question 7

which nucleotide bond is stronger

Answer 7

G-C

Question 8

which aa are necessary fro purine synthesis?

Answer 8

GAG
glycine
aspartate
glutamine

Question 9

NucleoSide

Answer 9

base + deoxyribose (Sugar)

Question 10

NucleoTide

Answer 10

nucleoside + phosphaTe

Question 11

leflunomide

Answer 11

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

Question 12

mycophenolate and ribavirin

Answer 12

inhibit IMP dehydrogenase

cannot make GMP from IMP

Question 13

hydroxyurea

Answer 13

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

Question 14

5-FU

Answer 14

inhibits thymidylate synthase

cannot make dTMP

Question 15

which drugs inhibits Dihydrofolate reductase

Answer 15

MTX
TMP
pyrimethamine
cannot regenerate THF therefore cannot make dTMP

Question 16

what step of nucleotide synthesis is imparied in ortic aciduria?

Answer 16

cannot combine ortic acid w/aspartate to make UMP

cannot make pyrimidines

Question 17

adenosine deaminase deficiency

Answer 17

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

Question 18

Lesch-Nyhan syndrome

Answer 18

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)

Question 19

HGPRT acroynm

Answer 19

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

Question 20

allopurinol and febuoxostat

Answer 20

xanthine oxidase inhibitors cannot make uric acid

Question 21

probenecid

Answer 21

increases excretion of uric acid in urine

Question 22

DNA topoisomerase

Answer 22

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

Question 23

DNA polymerase III

Answer 23

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

Question 24

DNA polymerase I

Answer 24

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

Question 25

telomerase

Answer 25

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

Question 26

Lac operon

Answer 26

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

Question 27

nucleotide excision repair

Answer 27

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

Question 28

xeroderma pigmentosum

Answer 28

prevents repair of pyrimidine dimers d/t UV exposure

Question 29

base excision repair

Answer 29

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

Question 30

mismatch repair

Answer 30

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

Question 31

nonhomologous end joining

Answer 31

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

Question 32

DNA/RNA/protein synthesis direction

Answer 32

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

Question 33

mRNA codones

Answer 33

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

Question 34

mRNA stop codones

Answer 34

UGA UAA UAG

Question 35

promoter sequence

Answer 35

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

Question 36

RNA polymerase I

Answer 36

makes rRNA (most numerous/Rampant)

Question 37

RNA polymerase II

Answer 37

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

Question 38

RNA polymerase III

Answer 38

makes tRNA (smallest/tiny)

Question 39

RNA polymerases

Answer 39

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

Question 40

alpha-amanitin

Answer 40

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

Question 41

rifampin

Answer 41

inhibits prokaryote RNA polymerase

Question 42

actinomycin D

Answer 42

inhibits RNA polymerases in both prokaryotes and eukaryotes

Question 43

RNA processing in eukaryotes

Answer 43

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

Question 44

anti-snRNPs

Answer 44

aka Smith Abs | SLE

Question 45

anti-U1 RNP abs

Answer 45

mixed CT disease

Question 46

tRNA structrue

Answer 46

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

Question 47

charging of tRNA

Answer 47

aminoacyl-tRNA synthetase checks to make sure matchis correct

Question 48

wobble

Answer 48

accuracy only required for first two base-pairs

Question 49

protein synthesis initiation

Answer 49

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

Question 50

elongation

Answer 50

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