Molecular Biology Part II: Gel Electrophoresis AP Lab 6

What you need to know! http://www.phschool.com/science/biology_place/labbench/lab6/intro.html

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

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

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)

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

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)

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?

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

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)