Part 2: DNA Structure, Replication, and Variation
DNA Replication and Recombination
of DNA strands allows each strand to serve as a
for synthesis of the
DNA replication in bacteria begins at the
The DNA helix is
by proteins called
which bind to the origin of replication and break the
bonds between the bases.
Producing of DNA polymers requires a
primer made by the
Polymerization is catalyzed by several DNA
occurs in the 5' to 3' direction by addition of one nucleotide at a time to the 3'
DNA synthesis is continuous along the
strand of the replication
but is discontinuous along the
strand. Synthesis is
The RNA primer is removed by
which replaces it with DNA
The Okazaki fragments are joined together by DNA
, which forms the missing phosphodiester bonds between the fragments.
Prokaryote DNA synthesis
Eukaryotic DNA synthesis is more complex than that in prokaryotes.
Eukaryotic genomes are
and contain multiple origins of
to allow the genome to be replicated in a few hours.
have been discovered; four partake in replication, the rest are involved in
Eukaryotic chromosomes are complexed with
that also need to be duplicated during DNA synthesis.
Eukaryotic chromosomes are
rather than circular, and pose a problem when terminating
Repeating sequences of DNA called
are synthesized by the
to prevent chromosome shortening in
in general involves DNA
along two chromosomes with sequence homology.
DNA recombination can also occur by
, caused by excision repair of a heteroduplex in meiosis.
Nov 15, 2008