primers

short RNA seq synth by primase and H-bonded to template

DNA polymerases

-fn

-direction

synthesize DNA in 5' to 3' direction

(reading is from 3' to 5')

also proofread

3'->5' exonuclease activity

vs

5'->3' exonuclease activity

3-5: proof-reading by DNA polymerase to correct mispaired nucleotides

5-3: remove primers from front of newly-formed strand

helicase

unwinds/separates DNA strand for replication

gyrases and DNA rep

relieve supercoils introduced by unwinding

SSBs (Single-stranded DNA-binding proteins)

bind to DNA during rep to prevent annealing

PRO DNA polymerases (3)

all have 3'->5' exonuclease activity (proofreading)

Pol I:DNA synth lagging strand, 5'->3' exonuclease activity (primer removal)--KLENOW FRAG.

Pol II: DNA repair

Pol III: synth leading strand, sliding clamp

Klenow fragment

location of primer removal by Pol I in prokaryotes (5'->3' exonuclease activity)

Sliding clamp

in prokaryotes, prevents Pol III from dissociating until DNA replication is complete

Ori (Origin of replication)

point at which PRO DNA replication begins

rep begins at Ori and proceeds in opp directions

BIDIRECTIONAL

Replisome complex

in PRO DNA replication

primosome (primases, ligases and helicases)

replisome (primosome plus SSBs, Pol III and Pol I

EU Ori

multiple sites, bidirectional (as in PRO)

replicons

DNA segments between Oris (EU)

EU DNA polymerases

Polymerase δ: high processivity (due to PCNA clamp), leading strand, 3'->5' exonuclease

Polymerase α: low processivity, lagging strand, primase fn, dissasembles nucleosome b4 rep

PCNA

EU homologue to sliding clamp in PRO

Replication Protein A (RPA)

EU homolog to PRO SSB

keeps two strands from annealing during rep

lagging strand looping in EU DNA rep

allows alpha and delta polymerase to dimerize and work on leading/lagging strands in same direction

when are histones synthesized?

during S phase, simultaneous w DNA replication

New DNA contains nucleosomes with parental and new histones

telomerase

reverse transcriptase that creates telomeres in new DNA (so that it doesn't continue to grow shorter and shorter with each replication)

reverse transcriptase

RNA-->DNA

most error-prone of DNA polymerases bc lack 3'->5' exonuclease activity (proofreading)

homologous genetic recombination

DNA recomb between homologous genes of chromosome pairs during prophase of meiosis-->genetic diversity

conservative site-specific recombination

bacteriophage dna insertion into bacterial chrom

homology not required

transposition (jumping DNA)

DNA recombination from one with to another within a chromosome

can inactivate or activate a gene depending on location of insertion