1. Sequencing and Copying DNA

2. Gel electrophoresis Used to separate DNA fragments by size Parts
Agarose gel (sponge-like matrix)
Electric current (pushes the molecules through the gel)
Buffer solution (maintain the pH and provide ions to conduct the current)
DNA fragments
Dye (usually ethidium bromide)

3. How it works
Charged DNA molecules move from the negative end to the positive end of the gel (down from the wells)
Smaller pieces travel faster/farther than larger ones

5. The gel is then stained
The size of the DNA fragments can be determined by comparing them to markers of known length
The DNA pattern can also be used to match DNA samples

6. DNA Sequencing Determines the sequence of the nucleotides
Dideoxynucleotides are used because they will stop the addition of nucleotides when copying DNA

7. The reaction mixture contains
- DNA to be sequenced (template DNA)
- free nucleotides
- free dideoxynucleotides
- an enzyme (Taq polymerase)
- primers

8. The Process
DNA is heated so the double helix denatures so it becomes single-stranded

9. The primers attaches to the single-stranded template DNA
Taq polymerase begins adding free nucleotides to build double stranded DNA

10. When a dideoxynucleotide is added to the DNA by the polymerase, no further nucleotides can be added
Eventually there are many pieces of DNA that end at different locations

11. The DNA fragments can be run through a gel and the sequence of nucleotides can be read

13. PCR Polymerase Chain Reaction Used to copy (amplify) DNA
Thermal Cycler

14. PCR Ingredients DNA to be copied (template) Primers Taq polymerase
dNTPs (deoxynucleoside triphosphates)
Buffer solution

15. Stages for PCR
Denaturation
Annealing
Elongation/Extension