molecular

Question 1

which AAs are in histones?

Answer 1

lysine

arginine

Question 2

what is H1?

Answer 2

linker protein

binds histone, nucleosome, linker DNA - stabilizes chromatin

Question 3

what does DNA methylation do?

Answer 3

template strand methylation of C and A –> mismatch repair can tell old from new
CpG island methylation –> represses transcription

Question 4

what does histone methylation do?

Answer 4

represses transcription

Question 5

what does histone acetylation do?

Answer 5

relaxes DNA coiling –> activates transcription

Question 6

which AAs are necessary for purine synthesis?

Answer 6

GAG
glycine
aspartate
glutamine

Question 7

which AAs are necessary for pyrimidine synthesis?

Answer 7

aspartate

Question 8

what does leflunomide do?

Answer 8

inhibits dihydroorotate synthesis - prevents formation of orotic acid in pyrimidine synth pathway

Question 9

what do mycophenolate and ribavirin do?

Answer 9

inhibit IMP DH in GMP synthesis - end of purine synth pathway

Question 10

what does hydroxyurea do?

Answer 10

inhibits ribonucleotide reductase - part of pyrimidine synth pathway

Question 11

what does 6MP/azathioprine do?

Answer 11

inhibit de novo purine synthesis

Question 12

what does 5FU do?

Answer 12

inhibits thymidylate synthase –> decreased dTMP

Question 13

what do methotrexate, TMP, and pyrimethamine do?

Answer 13

inhibit dihydrofolate reductase (species specific - MTX in humans, TMP in bacteria, pyrimethamine in protozoa)
- decreased dTMP

Question 14

what does probenecid do?

Answer 14

increases uric acid excretion in urine

Question 15

what do allopurional and febuxostat do?

Answer 15

block xanthine oxidase –> prevent build up of uric acid

Question 16

AR cause of SCID?

Answer 16

adenosine deaminase deficiency

imbalance of nucleotide pool –> DNA synth prevented

Question 17

intellectual disability, self-mutilation, aggression, dystonia, hyperuricemia, gout?

Answer 17

Lesch-Nyhan, XLR
HPGRT absent
excess hypoxanthine and guanine –> excess uric acid prodcution and excess DE NOVO purine synthesis

tx: allopurinol or febuxostat

Question 18

what proofreader function does DNA pol III have?

Answer 18

3’-5’ exonuclease

Question 19

what functions does DNA pol I have?

Answer 19

same as DNA pol III + RNA 5’-3’ exonuclease

Question 20

what substitution is made in sickle cell dz?

Answer 20

glutamate –> valine

Question 21

what is the fn of glucose in the lac operon?

Answer 21

low glu –> increased cAMP –> activation of CAP –> transcription induction

Question 22

what is the fn of lactose in the lac operon?

Answer 22

high lactose –> repressor removed from operator site –> transcription

Question 23

what DNA repair process is deficient in xeroderma pigmentosum?

Answer 23

nucleotide excision repair (G1)

Question 24

what DNA repair process is deficient in HNPCC?

Answer 24

mismatch repair (G2)

Question 25

what DNA repair process is deficient in ataxia telangiectasia and Fanconi anemia?

Answer 25

dsDNA break repair - nonhomologous end joining

Question 26

what are the mRNA stop codons?

Answer 26

UGA - u go away UAA - u are away UAG - u are gone

Question 27

what does RNA pol I do?

Answer 27

makes rRNA | most numerous

Question 28

what does RNA pol II do? what inhibits it?

Answer 28

makes mRNA opens DNA at promoter largest inhibited by alpha-amanitin (mushrooms) --> hepatotoxicity

Question 29

what does RNA pol III do?

Answer 29

tRNA | smallest

Question 30

what are post-transcriptional modifications of hnRNA?

Answer 30

capping polyadenylation splicing --> mRNA

Question 31

what are cytoplasmic P bodies?

Answer 31

mRNA quality control | exonucleases, decapping enzymes, miRNA

Question 32

which are auto-Abs to snRNPs?

Answer 32

anti-Smith | anti-U1 RNP

Question 33

what sequence do AAs bind on tRNA?

Answer 33

CCA at 3' end

Question 34

what sequence is in the T arm of tRNA?

Answer 34

thymine pseudouracil cytosine | necessary to bind ribosome

Question 35

what is in the D arm of tRNA?

Answer 35

dihydrouracil | needed for recognition by aminoacyl-tRNA synthetase

Question 36

which are the eukaryotic ribosome subunits?

Answer 36

40s, 60s --> 80s

Question 37

which are the prokaryotic ribosome subunits?

Answer 37

30s, 50s --> 70s

Question 38

what are initiation factors?

Answer 38

help assemble 40s subunit, released when mRNA and 60s assemble

Question 39

what is fMet?

Answer 39

translation of start codon in prokaryotes | stimulates neutrophil chemotaxis