1. Molecular Biology Part II: Gel Electrophoresis
AP Lab 6

2. What you need to know!

3. DNA Finger Printing
Forensics, medical, and paternity cases use DNA finger printing
DNA is cut with RE into fragments
Gel Electrophoresis is a technique that separates and moves the molecules through a gel-like matrix exposed to electrical current
Molecules move according to size and charge

4. Gel Electrophoresis
DNA fragments separate according to size in an agarose gel
DNA is negatively charged due to their phosphate groups
DNA is drawn toward the positive end of an electric current (opposites attract)
DNA runs to red
Fragments move according to their size through the agarose gel matrix
The smaller the piece, the faster it travels

5. Critical Components
Agarose gel: provides matrix with microscopic pores (smaller molecules travel more easily)
Running Buffer: conduction medium (salt water solution that carries the current between electrodes)
Wells: formed by comb (holds samples to be sorted)
Samples: substances added to wells that will travel through the gel (marker and DNA fragments)

6. Critical Components
Electric Current: runs through the buffer and gel creating an electrically positive and negative side of the gel
Bands: DNA fragments that have the same size collect to form bands (small bands farthest from the wells, large bands closest)
Marker: sample of known fragments used as reference points

7. General Concept
Every individual’s DNA has very specific genetic variations/mutations
Therefore DNA base sequences between people varies (except identical twins)
If DNA is exposed to RE, it will fragment the DNA into varying sizes (different sizes for each person)
The different sized DNA fragments will spread across the gel into bands
Measuring the distance each band migrated reveals a distinct pattern to each individual (fingerprint)

8. Forensics Sample A was from the crime scene.
Sample B was from Ayeete P. Za.
Sample C was from Jorge Uv D. Jungel.
Sample D was from the Senator Watson, of Missouri.
Who committed the felon?

9. Paternity Cases
Individual number Distance migrated (mm) of each DNA band on gel
1 20.5, 27.5 (child)
2 24.5, 27 Man 1
3 20.5, 24.5 Man 2
4 20, 26.5 Man 3

10. Medical Research
DNA analysis in conjunction with pedigrees can track genetic disorders in a family
Additionally, genetic analysis can determine heredity as far back as the dawn of human kind in Africa (genome project)