Laboratory

1
Laboratory 11

• DNA Electrophoresis
• J. Ellen Lathrop-Davis

2
DNA Structure

• Watson and Crick (1953)
• Double-stranded
• Nucleotides
• Deoxyribosephosphate backbone
• Nitrogen bases
• Purines (double-ringed)
• Pyrimidines (single-ringed)
• Hydrogen bonding
• AT CG

3
DNA Central Dogma

• sequence hypothesis DNA sequence and amino acid
  sequence (within protein) are both linearly
  arranged
• central dogma DNA ? RNA ? protein
• DNA ? DNA replication
• DNA ? RNA transcription
• RNA ? protein translation

4
DNA Fingerprinting

• application of molecular genetics techniques
• extract and isolate DNA from sample (must have
  living cells saliva with buccal cells, hair
  follicles, blood, semen)
• exposure of DNA to restriction endonuclease
  enzymes
• hydrolyze DNA at specific sequences
• produces DNA subsets called restriction fragment
  length polymorphisms (RFLPs) because each
  persons DNA has slightly different sequences
• of fragments number of cuts 1

5
PCR

• polymerase chain reaction
• used to make additional copies of DNA from small
  sample
• alternates heating to dissociate strands with
  polymerase activity to synthesize new strands
  based on old strands

6
Agarose Gel Electrophoresis

• uses electrical current to move DNA through
  agarose (polysaccharide) gel
• fragments separate based on size
• DNA is negatively charged ? migrates toward
  cathode (positive pole) (buffer makes them all
  DNA fragments electrically equal)
• positively charged molecules move toward anode
  (negative pole)
• fragments are linear
• smaller fragments travel faster, therefore, are
  found farther from origin

Nice website for uses http//www.bioteach.ubc.ca/
MolecularBiology/DNAfingerprint/
http//www.biologycorner.com/images.php