DNA REPLICATION
1. WHAT DOES IT MEAN TO REPLICATE?
Replicate means to duplicate or copy.
DNA REPLICATION SUMMARY
When one DNA molecule is
duplicated (copied) to make
two new molecules DNA.
Start with one molecule of
DNA.
End with two new molecules
of DNA. Exact Copies
WHAT ORGANISMS GO THROUGH DNA
REPLICATION?
All living things go
through DNA Replication.
PURPOSE
Why would your cells need to make
copies of its DNA?
PURPOSE OF DNA REPLICATION
DNA replication occurs when
new or more cells are needed.
- Asexual (mitosis)
Examples:
-Sexual (meiosis)
Examples:
Everything in the cell is
replicated- including DNA
DNA REPLICATION: STEP BY STEP
3 steps to DNA replication
1.
2.
3.
Unzip/Separate
Building/Adding
2 New Copies
Some steps require enzymes (proteins)
to speed up the process
DNA REPLICATION IN REAL TIME
http://www.youtube.com/watch?v=WNqMsn45DE&safety_mode=true&persist_safety_
mode=1&safe=active
STEP ONE: SEPARATE OR UNZIP
Description: DNA is separated into
two strands
Materials: An enzyme: DNA
Helicase “unzips” the
DNA
STEP TWO: BUILDING
Description: Nucleotides are added to
the both of the two
separated strands
Two Materials: -A. An enzyme: DNA
Polymerase adds
nucleotides to the old strand.
-B. Free Nucleotides
STEP THREE: NEW COPIES
Description: Two new copies (exact
duplicates) are made.
SUMMARY
1.
2.
3.
Separate
Build
Two new copies
WHICH MODEL OF DNA REPLICATION DO
YOU THINK DNA GOES THROUGH?
DNA REPLICATION MODEL
DNA replication is known as semi-conservative
What does “semi-” mean?
-half or partial
What does “conservative” mean?
-using old materials, not changing
DNA REPLICATION IS SEMI-CONSERVATIVE
BECAUSE….
The 2 new molecules of DNA are each
made of:
-one old “parent” strand
-one newly made “daughter” strand
ACCURACY OF REPLICATION

This replication process only makes a
mistake once every billion nucleotides

DNA polymerase has a built in
proofreader (spell-check) that checks for
mistakes and fixes them immediately!
WHICH MODEL OF DNA REPLICATION DO
YOU THINK DNA GOES THROUGH?
TABLE CHALK REVIEW:
1.
2.
3.
1.
2.
3.
4.
DIRECTIONS
Name the three steps
Draw a diagram
Label the “materials”
Show me to get credit
Step 3: Use different colors to
show the difference between
the parent strand and the new
daughter strand of DNA