Molecular I Flashcards
DNA and histone charges
DNA - negative
histone - positive
histone AAs
arginine and lysine
H1 histone
linker
binds nucleosone - stabilizing chromatin
DNA and histone synthesis
S phase
heterochromatin
dense DNA
inactive
ex. barr bodies - inactive
euchromatin
loose DNA
active
DNA methylation
inhibit transcription
CpG islands
DNA methylation
-inhibit transcription
nucleosome
DNA wrapped around histone
histone methylation
repress DNA transcription
histone acetylation
relax DNA coil
-allow transcription
purine
A
G
2 rings
pyrimidine
C
T
U
1 ring
bonds purine vs. pyrimidine
C-G = 3 A-T = 2
CG stronger - higher melting temp
AA for purine synthesis
glycine
aspartate
gultamine
nucleoside vs. nucleotide
side - base and sugar
tide - base, sugar, and phosphate
hydroxyurea
inhibit ribonucleotide reductase
-inhibit pyrimidine pathway
6 mercaptopurine
inhibit de novo purine synthesis
purine synthesis
5 fluorouracil
inhibit thymydilate synthetase
pyrimidine synthesis
methotrexate
inhibit DHFR
trimethoprim
inhibit DHFR
pyrimethamine
inhibit DHFR
leflunomide
inhibit dihydroorate DH
mycophenolate
inhibit IMP DH
purine synhesis
ribavirin
inhibit IMP DH
purine synthesis
temporary base in pyrimidine synthesis
orotic acid
allopurinol
inhibit xanthine oxidase
febuxostat
inhibit xanthine oxidase
probenecid
increased uric acid excretion in urine
adenosine deaminase deficiency
major cause auto rec SCID
excess ATP and dATP - imbalanced nucleotide pool
prevent DNA synthesis - decreased lymphocyte count
redundant genetic code
most AA coded by multiple codons
lesch nyhan syndrome
defective purine salvage
absent HGPRT
excess uric acid
clinical intellectual disability, self mutilation, aggression, hyperuricemia, gout, dystona
tx lesch nyhan
allopurinol
febuxostat
helicase
unwind DNA
single strand binding protein
prevent reannealing of separated DNA strands
fluoroquinolones
inhibit topoisomerase II - DNA gyrase
topoisomerase
fix supercoliing
primase
add RNA primer - on which DNA polymerase III can initiate replication
DNA polymerase III
prokaryote only
5 > 3 synthesis
3 > 5 exonuclease
DNA polymerase III vs. I
III - elongate leading strand - 5 > 3 synthesis
-and 3 > 5 exonuclease
I - degrade RNA primer - replace with DNA
-and 5 > 3 exonuclease
direction of synthesis of DNA
read 3 > 5
synthesized 5 > 4
DNA polymerase I
excise RNA primer with 5 > 3 exonuclease
DNA ligase
formation of phosphodiester bonds within strand of dsDNA
join okazaki fragment
telomerase
add DNA to 3’ end chromosome
avoid loss of genetic material
RNA dependent DNA polymerase
transition
purine to purine or pyr to pyr
transversion
purine to pyr
glucose not available to E. coli - but lactose is
lac operon activated
low glucose - increased adenylyl cyclase - increase cAMP
-activation of CAP - increased transcription
high lactose - unbind repressor protein - increased transcription
strong expression of lac operon
low glucose
high lactose