Download DNA polymerase I

Chromosomal Landscapes
Refer to Figure 1-7 from Introduction to Genetic Analysis, Griffiths et al., 2012.
Human Chromosomal Landscapes
Refer to Figure 1-8 from Introduction to Genetic Analysis, Griffiths et al., 2012.
Molecular Basis for
Relationship between Genotype and Phenotype
genotype
DNA
transcription
DNA sequence
replication
RNA
translation
protein
function
phenotype
organism
amino acid
sequence
Replication
Replicationof
ofDNA
DNAisis
semiconservative.
semiconservative.
Each
Eachstrand
strandserves
serves
as
asaatemplate.
template.
The
Thetwo
twostrands
strands
separate
separatefrom
fromeach
each
other
otherwhen
when
hydrogen
hydrogenbonds
bonds
are
arebroken.
broken.
Refer to Figure 7-11 from Introduction to Genetic Analysis, Griffiths et al., 2012.
New
Newstrands
strandsare
are
synthesized
synthesizedby
bythe
the
addition
additionof
ofnucleotides
nucleotides
with
withbases
bases
complementary
complementaryto
to
those
thoseof
ofthe
thetemplate.
template.
DNA
DNAreplication
replicationisis
discontinuous.
discontinuous.
Two
Twoidentical
identicaldouble
double
helices
helicesresult.
result.
Refer to Figure 7-12 from Introduction to Genetic Analysis, Griffiths et al., 2012.
DNA
polymerization
requires DNA
polymerase.
Refer to Figure 7-15 from Introduction to Genetic Analysis, Griffiths et al., 2012.
DNA Polymerases
At least 5 DNA polymerases are known in E. coli .
DNA polymerase I (pol I):
•
•
•
adds nucleotides in 5’ to 3’ direction
removes mismatched based in 3’ to 5’ direction
degrades double-stranded DNA in 5’ to 3’ direction
DNA polymerase II (pol II):
•
repairs interstrand cross-links
DNA polymerase III (pol III):
•
catalyzes DNA synthesis at replication fork in
5’ to 3’ direction and only adds nucleotides at 3’ end
of growing strand
Overview of DNA Synthesis
DNA polymerases synthesize
new strands in 5’ to 3’
direction.
Primase makes RNA primer.
Lagging strand DNA consists of
Okazaki fragments.
In E. coli, pol I fills in gaps in
the lagging strand and removes
RNA primer.
Fragments are joined by DNA
ligase.