 Happy Monday 
• On your Bellwork Sheet write “Finish
Vocabulary Project”
• Take about 10 minutes to finish and
turn in your Vocabulary Project
• Quiz Tomorrow over DNA Structure
Vocabulary
Standard:
…describe how information…is
carried in the DNA (B.6A)
Essential Question:
How can I describe DNA
replication?
Replication:
making an
identical copy
Before a cell
divides, it must
copy its DNA.
Why make a copy?
• cells copy their DNA so that every new
cell will have the exact same DNA in its
nucleus
*DNA never, ever, ever, ever, EVER leaves
the nucleus!*
•replication begins at a single point on the double helix
•proceeds in two directions (along both strands) until
complete
•ALWAYS occurs in the nucleus
Why does DNA replication always
happen in the nucleus?
•replication happens in a 5’  3’ direction
•enzymes are used to add new base pairs to
both strands
•end result = two identical DNA molecules
•enzymes used include:
−helicase = unzips the double helix
−DNA polymerase = creates the new DNA polymer
Why is the unzipping enzyme called
“helicase”?
(remember, enzymes are named after
their job!)
•each half of the DNA double helix has everything it
needs to recreate the other half
•the two strands are complementary
•complementary = something that completes or
enhances something else
If you only have half of a DNA
double helix, how can you fill in the
other half?
•Semi-conservative: each replicated DNA
molecule is made of one original (OLD)
strand and one complementary (NEW)
strand
The complementary strand for
AGGCTAAGTCGGTA is
TCCGATTCAGCCAT…
Your turn…
Write the complementary strand for
the following sequence:
CGGAATTCGGCCTTAAGC
How does the structure of DNA
make it easy to replicate?
DNA Replication Foldable
1. Fold the edges of your paper toward the BACK
along the dotted lines.
2. Now fold the two sides in to meet in the middle
(also marked with a dotted line).
3. Using the given ORIGINAL strand, complete the
complementary strand.
4. Open your edges. Now “replicate” the DNA by
filling in the two new strands.
5. Put your name on your paper and turn it in! I will
keep them until next week, when we will add
another step.