Bellwork: Write the question and answer. Explain what “complementary” means:_______________________. “A” pairs with___using_________bonds. “C” pairs with___using ________bonds. *USE YOUR NOTES!!!

Bellwork: Write the question and answer. Explain what “complementary” means: Complementary means to pair with or complete something else. “A” pairs with_T_using_hydrogen_bonds. “C” pairs with_G_using _hydrogen_bonds. *USE YOUR NOTES!!!

Standard: …describe how information…is carried in the DNA (B.6A) Essential Question: How does DNA replication occur?

TODAY… We will discuss how DNA replicates itself

Replication: to make an identical copy Before a cell divides, it must copy its DNA. Why?cell

Why make a copy? So that every new cell will have the exact same DNA in its nucleus Same DNA=Same instructions for all cells *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?

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 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 strand and one new (complementary) strand

The complementary strand for AGGCTAAGTCGGTA is

The complementary strand for AGGCTAAGTCGGTA is TCCGATTCAGCCAT…

Your turn… Write the complementary strand for the following sequence: CGGAATTCG GCCTTAAGC

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.