KEY CONCEPT The polymerase chain reaction rapidly copies segments of DNA.

1. KEY CONCEPT The polymerase chain reaction rapidly copies segments of DNA.

2. target sequence of DNA PCR uses polymerases to copy DNA segments. • PCR makes many copies of a specific DNA sequence in a few hours. • PCR amplifies DNA samples. • PCR is similar to DNA replication.

3. DNA strands primer1 polymerase primer 2 nucleotides PCR is a three-step process. • PCR uses four materials. • DNA to be copied • DNA polymerase • A, T, C, and G nucleotides • two primers

4. PCR animation • Kary Mullis • Challenges: • How do we separate DNA without helicase? Think, how are DNA base pairs held together? • How does heating the sample cause problems for enzymes? • Lucky for us, Kary was a real man of genius. • Enzymes have an optimum temperature • As kinetic energy goes us, the rate of the reaction goes up to a certain extent • Kary used an enzymes from a bacterium that thrives at hot temperatures, so heating a sample of DNA to break the H bonds does NOT denature the protein!

5. DNA strands primer1 polymerase primer 2 nucleotides • The three steps of PCR occur in a cycle. • heat is used to separate double-stranded DNA molecules • primers bind to each DNA strand on opposite ends of the segment to be copied • DNA polymerase binds nucleotides together to form new strands of DNA

6. Each PCR cycle doubles the number of DNA molecules.