January 13, 2015 Objective:  To be able to explain and model how DNA replicates  To describe how the structure of DNA relates to how it replicates Journal: On a separate piece of paper draw a nucleotide and label it’s three parts.

DNA Replication

Replication A. Process by which DNA makes an exact copy of itself B. Results in 2 identical DNA molecules

Discussion Question Turn to someone next to you and come up with an answer to the following question. Why would an organism want two identical molecules of DNA?

Why replication?? Copies the genetic code Allow new cells to have exactly the same genetic info as old cells  This is how traits are passed on Can be used to make new cells

How does replication work? Step 1: Since the genetic code is on the inside of the DNA ladder, the helix must first unwind and unzip using an enzyme called DNA helicase Forms a replication bubble

How Replication Works Step 2: An enzyme called DNA polymerase then matches up complementary DNA nucleotides with the open ones on each DNA strand

How Replication Works Step 3: DNA polymerase then bonds/glues the sugar and the phosphate to each other forming a complete strand of DNA

How Replication Works Results: Each new DNA strand contains ½ of the original strand and ½ new nucleotides  This is known as semiconservative because each strand has half the old strand.

Sites of Replication Replication occurs at multiple sites along same DNA strand  Human DNA has about 3 billion base pairs  Speeds up the process

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