Med Genomics Flashcards
the phosphate group is responsible for the strong ___ charge of the nucleic acid
negative
parental double helix divides into two double helix DNA with one parental strand in each of the two double helices
semiconservative replication of DNA
describe eukaryotic and prokaryotic DNA
eukaryotic - very long with multiple origins of replication
prokaryotic - circular with one origin of replication
bind to specific nucleotide sequences at ORIGINS of replication (area usually rich with A&TS) - ATP required - causes double stranded DNA to melt causing strands to separate to form 2 single stranded DNA
DnaA protein
also called helix destabilizing proteins; protein that protects DNA from nucleases that cleave the single stranded DNA
Single stranded DNA binding proteins (SSB)
binds to single stranded DNA near replication fork and move further into double stranded regions of DNA forcing the strands apart/unwinding the double helix - ATP required
DNA helicases
replication of double stranded DNA is ____
bidirectional
what results from DNA strand seperation
positive supercoiling
what is responsible for removing supercoils in the helix
DNA topiosomerases
actions inlcude - nuclease (cut) and ligase (reassemble)
direction of DNA replication
reading - 3 –> 5
create - 5 –> 3
reading when your 3 is ok, but creating a fort at 5 sounds more fun
strand that is being copied in the direction of the advancing replication fork is called
leading strand - synthesized continuously
strand that is being coped in the direction away from the replication fork is called
lagging strand - synthesized discontinuously - ozaki fragments
what are short stretches of discontinuous DNA called
ozaki fragments
DNA polymerase 3 has ______ activity (building)
5 –> 3 polymerase activity (builds) - antiparallel to parental strand
DNA polymerase 3 has ______ activity (prooofreading)
3 –> 5 exonuclease activity (proofreads)
what activity is used to exicse mismatched nucelotides during proofreading of newly synthesized DNA
3 –> 5 exonuclease
what is a short double stranded region consisting of RNA base paired to the DNA template
RNA primer
what synthesizes the short stretches of RNA (ten nucelotides long) and complementary and antiparallel to DNA template
primase (specific RNA polymerase)
DNA polyermase 3 will recognize the ____ and begin to synthesize DNA
RNA primer
DNA 3 continues to synthesize DNA on lagging strand until it is blocked by _____; then the answer will be excised and the gap will be filled by ____
RNA primer
DNA polymerase 1
As DNA polymerase replaces RNA with DNA in the ___ direction, synthesizes DNA in the ___ direction and proofreading the new strand in ____ direction
replace RNA with DNA - 5 –> 3 exonuclease activity
sythesizing - 5 –> 3 polymerase activity
proofreading - 3 –> 5 exonuclease activity
ozaki fragments are joined by what enzyme and bond
DNA ligase - formation of phosphodiester bond
a multisubunit enzyme (one subunit has primase acitvity) which INITIATES strand synthesis on the leading strand and beginning of each ozaki fragment on the lagging strand
pol alpha
a protein recruited to COMPLETE DNA synthesis on leading strand and elongate each ozaki fragment
pol delta
if didnt work properly it would cause cancer - mitotic clock
telomerase
removal of abnormal bases involves what
glycosylase
a thymine without the methyl group is what
uracil
inherited syndromes with defects in DNA repair
- colon cancer
- cellular UV sensitivity/ skin cancer
- colon cancer - mismatch repair
- UV sensitivity - nucleotide excision repair *********
where does translation occur
cytosol!!
not nucelus
functions of RNA 1,2,3
creates precursor to what??
1 - large ribosomal RNA
2 - messenger RNA
3 - transfer RNA, small ribosomal RNA
mRNA and tRNA are synthesized where?
ribosomal RNA?
mRNA and tRNA - nucleoplasm
rRNA - nucleolus
what acts over long distances to reduce the level of gene expression
silencers and enhancers
tRNA contains what
ACC
bases added
explain introns and extrons
introns - intervening sequence
exons - expressive info
what forms a splicesome
primary transcript combines with snRNPs fold into complex
what disease cause antibodies against snRNPS
systemic lupus erythrematosus
what forms the mature mRNA
exons
characteristics of genetic code
specificity
universality
degeneracy
non overlapping and commaless
when genetic code is redundant where some amino acids have more than one triplet coding for it (ex. arginine)
degeneracy
Components required for translation
amino acids
atp and gtp
protein factors
what is required in the last two steps of initiation and translation
GTP
translocation - after the petide bond is formed, the ribosome advances three nucelotides toward the 3 end of the ____
mRNA
initiation codon aug is recognized by special initiator tRNA that enters the ___
p site
formation of peptide bonds is catalyzed by what
peptidyltransferase - found in rRNA 28S found in 60s ribosomal subunit - ribozyme because rRNA catalyzes the reaction
termination occurs when the three termination codon moves into the __
a site
termination codon is recognized by a _____ that activates and release new peptide
release factor
posttranslational modification of polypeptide chains
- phosphorylation
- glycosylation
- hydroxylation
- carboxylation
phosphorylation - serine and tyrosine
glycosylation - o and n linked
hydroxylation - proline, collagen, vit C
caboxylation - glutamate and vit K
protein degradation
protein tagged for degradation with molecule of ubiquitin
ubiquinated proteins are recognized by cytosolic proteasome which unfolds the protein and transports the protein to proteolytic core
unlike DNA polymerase, RNA polymerase …
does not require a primer and has no known endonucleases or exonucleases, therefore cant repair mismatch
