BELL WORK:

Use the following words to fill in your bubble map:

• Adenine (A)• Base• Cytosine (C)• Deoxyribose• DNA• Guanine (G)

• Hydrogen• Nucleic acid• Nucleotide• Phosphate• Thymine (T)

CO: I will understand and describe the stages of DNA replication.

LO: I will annotate notes about DNA replication, and practice replication using a foldable.

Before a cell divides, it copies

its DNA in a copying process

called replication.

DNA replication begins at a single point in the sequence and proceeds, in two directions, until the entire strand (chromosome) is replicated. This takes

place in the nucleus.

Why does DNA replication always happen in the nucleus?

A number of different enzymes (helicase, DNA polymerase, DNA ligase, primase) are used to match both

sides of the DNA ladder to new base pairs in a 5’ 3’ direction resulting in two identical DNA molecules.

A special enzyme (helicase) is used to unzip the DNA molecule.

DNA Polymerase brings nitrogen bases to the new strand.

Why is the unzipping enzyme called “helicase”?

(remember how enzymes are named!)

Each strand of the DNA double helix has all of the information needed to recreate the other half (base pairing rules).

Because each strand can be used to make the other strand, the strands are said to be complementary.

What does the word “complementary” mean?

How does this apply to DNA strands?

Because each strand after DNA replication is made from half the original strand and half new, it is referred to as the semi-conservative model

of replication.

The complementary strand for AGGCTAAGTCGGTA is

TCCGATTCAGCCAT…

Your turn…

What is the complementary strand for the following:

CGGAATTCGTCG

GCCTTAAGCAGC

How does the structure of DNA make its replication easy?

DNA Replication Foldable1. 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.

Silent Reading

• You should be reading!!

•No talking, no music. Silent means you are quiet!