DNA Replication
DNA Replication
 Replication: The process before a cell divides, it
duplicates and copies its DNA. DNADNA
 Remember: Each strand can be used to make the
other strand, the strands are said to be complementary.
The Replication Process
 Replication occurs in late interphase of the cell cycle.
 During Replication
 DNA molecule separates or unzip into two strands which
serve as a template
 Produces two new complementary strands following the
base pairing rule
The Role of Enzymes in
Replication
 Enzymes aid in:
- “unzipping” DNA molecule by breaking the hydrogen
bonds.
- “zipping” DNA molecule back together.
 Enzymes involved in Replication
 Helicase: An Enzyme that unzips the DNA into two
strands.
 DNA polymerase: An enzyme that joins individual
nucleotides to produce a new strand of DNA. Also
“proofreads” each new DNA strand.
Other Enzymes Used in
Replication
 Telomeres- DNA at the tips of chromosomes. (difficult
to replicate)
 Telomerase: Add short, repeated DNA sequences to
the telomeres. Help prevent genes from being
damaged or lost during replication. Involved in aging.
Prokaryote Replication
 Prokaryote have a single, circular DNA.
 Replication
 Starts when regulatory protein binds
 Starts at a single point and proceeds in two directions
until entire chromosome is copied
Eukaryotic Replication
 Eukaryotic chromosomes are much larger than
prokaryotes.
 Replication
 May begin at dozen or even hundreds of places on DNA
 Proceeds in both directions until each chromosome is
copied.
DNA Replication Review