Chapter 12.3 (Pgs: 350-353):
DNA Replication
The Replication Process
1. DNA separates into two strands
- Accomplished by the enzyme
helicase
- Creates a replication fork
- Each strand is a template for a new
one
The Replication Process
2. New bases are added
- Accomplished by the enzyme DNA
polymerase, which also proofreads
DNA
- Follows the rules of base pairing
- Moves in opposite directions
The Replication Process
3. Two identical copies are created
- Each copy has an original strand and a new strand
The Replication Process
1. DNA separates into two strands
- Accomplished by the enzyme helicase
- Creates a replication fork
- Each strand is a template for a new one
2. New bases are added
- Accomplished by the enzyme DNA
polymerase, which also proofreads DNA
- Follows the rules of base pairing
- Moves in opposite directions
3. Two identical copies are created
- Each copy has an original strand and a
new strand
Differences in DNA Replication
- Prokaryotes have a single
circular chromosome
- Replication begins at one point
and continues in two directions
- Eukaryotes have multiple linear
chromosomes
- Replication begins in multiple
places on a chromosome and
continues in both directions
Telomeres
- The tips of eukaryotic
chromosomes
- The ends of
chromosomes are
difficult to copy and can
get cut off
- The enzyme telomerase
can repair the ends and
keep the ends from
becoming lost or
damaged