dna wys to replicate
- conservative, two strans stay together and two new made
- semi conservvative
- dispersive. bits of parent in daughter
*proved by 14N and 15N crap
dna pol I
- one chain w weight of 110,000
- needs a primer of single strange dna or rna w free 3’ OH (datp, dttp, dctp, dgtp)
activities
1) dna replicase
2) exonuclease and proofreader (1 at a time)
3) also remove primer
nearest neighbor base frequenncy analysis
- dna is complimentary/ antiparallel
- add bases, use an exonuclease to cut it, then determine the radioactivity to find % of pairs
- apc= gpt NOT apg =tpc
DNA pol III
in vivo in bac
- does 5/ to 3’
- good at low temp??
okazaki
- endonuclease makes a nick
- primase ads primer
- ligase makes last phospho bond
- synthesize 5’ to 3’
how to relieve strain on dna
- gyrase which is topoisomerase
- helicase unwinds dna and binding proteins keep it apart
modify dna for self id
- epigenetics like adding methl to prevent nuclease attack
repair of dna
- thymine dimer
- involves pol I and II
1) endo nuclease makes cut
2) exonuclease clips of damage
3) polymerase
4) ligase
sediment coefficient
trna is 4s
- higher means larger
rrna
- make up ribosome
- support structure during protein synth and make peptide bonds
small rna
- small rna play regulatory role in transcription
dna rna hybrid
when you heat them, realize that rna is denser than dna
- so when they cool, they make hybdrid which is more dense than dna alone
dna dependent rna pol
- nucleotides added to 3’ end of rna
- needs dna template but no primer
- only one strand made
rna synthesis steps
1) binding: pol binds dna. 1st nuc iS PURINE
2) initiation: 1st bond
3) elongation
4) termination: release of rna
rna pol subunit B
dna binding, binds rifampicin, active site
rna pol subunit B’
dna binding
rna pol subunit a
template site selection
rna pol core enzyme
- a bb’ portion
- transcribes dna randomly
rna pol holoenzyme
- holoenzyme is with sigma subunit too
- results in selective transcription at promoter regions
promoter region
- initiation complex starts at promoter region, upstream from gene (TATA box or palindrome)
- also dna can be weird shaped in this region (called cruciform)
rifampicin
- drug inhibits formation of first bond
- only in prokarya
rho
- termination factor
