Hi,
As far as I understand, this topic is about DNA replication when organisms copy their number of DNA. This process normally happen during cell division. (Please don't confuse this with transcription and translation)
I think the DNA polymerase III haloenzyme that you mentioned is part of the multisubunit assembley of protein complexed in E.coli . It is also known as replisome, not to be confusing with the name DNA polymerase which is enzyme.
http://en.wikipedia.org/wiki/Replisome
I will summarise the process of DNA replication briefly in here too. I hope it will make it much more clearer so you can of polymerase in this process.
For DNA replication to happen, it requires necessary enzymes/protein complexes. The main enzymes are:
Initiator protein
DNA helicase : unwinding the double helix
DNA polymerase(There are 6 different family A, B,C, D, X, Y and RT) : synthesis the nucleotides in the exonuclease 5'to 3' direction
RNA polymerase (different types depend on prokaryotes or eukaryotes) Main types in eukaryotes are I, II and III
Topoisomerase
Telomerase
DNA ligase
Stage of DNA replication
1.initiation : the initiator protein open the double strand DNAand recruite helicase to unwind the double stranded DNA
: once the single-strand DNA is formed, the SSB protein ( single stranded binding proteins)
: initiation is very restricted and happens only once per cell division.
2.elongation : Once initiation starts, and the replication machinery is in place, replication start.
: By this time, DNA double strand are seperated into leading strand and lagging strand.
* : DNA polymerase can only added nucleotide to the 3' end of the strand, it required short stretch of RNA primer at the start.
: RNA primer is degraded.
: two protin complexes involves for elongation : clamp loader and sliding clamp
:Because DNA can only be synthesised in the 5'to 3' direction, if this happens both strand of DNA will be synthesied into opposite direction. To overcome this problem the lagging strand is synthesis in a short stretch called Okazaki fragment and joined into continuous strand. Enzyme DNA ligase can link the pieces of DNA together.
3.termination : depend on type of chromosome ( if it is linear or circular)
I hope this can help you understand this process more.
