Forensics Test 3

Front 1

Techniques for Separating DNA (3)

Back 1

1) Electrophoresis
2) Gel Techniques
3) Capillary Techniques

Front 2

Electrophoresis

Back 2

Separates DNA using electricity
-Anode (attracts DNA)
-Cathode (repels DNA)
(DNA IS NEGATIVELY CHARGED)

Voltage=amt charge
Higher voltage=faster DNA

Matrix Arranges Molecules based on DNA/Pore size

Front 3

Agarose Gel

Back 3

-Works Faster (larger pores)
-Works with RFLP/PCR
-Uses Comb
-Blue dye added to sample
-Smaller DNA moves faster through matrix (DNA separates by size)
-DNA separates as it passes through pores
(HORIZONTAL GELS)

Front 4

Acrylamide Gel

Back 4

-Slower (smaller pores)
-Useful for STRs
-Higher resolution
-polymerization activated by adding TEMED
-Create thin matrix between sliding plates
-AVOID BUBBLES in order to read
(VERTICAL GELS)

Front 5

SIZE STANDARDS

Back 5

To have a relative size to compare to, run size standards
-FOR GELS: run in adjacent lane
-FOR CAPILLARIES: run in same lane with diff fluorescent color

Front 6

Advantages of Capillaries vs Gels (6)

Back 6

1)No gels to pour
2)Saves time, money and sample
3)Can be fully automated
4)Less sample is used
5)Detection of bands is done immediately
6)Higher voltage allows separation to be completed within minutes rather than hours

Front 7

Problems With Gels

Back 7

1)Labor intensive
2)Bubbles waste time/materials
3)Acrylamides are dangerous neurotoxins
4)Have to be careful when loading into lanes

Front 8

IDEAS As to How DNA Separates while traveling through a Matrix

Back 8

1) Ogsten Sieving: behavior of molecules smaller than pores
-DNA molecule like a tangle of thread (smaller molecules fit into more pores/move faster) tumbling its way through the pores.

2) Reptation: Behavior of molecules larger than pores
-DNA molecule like a snake (slithers through matrix) longer the DNA strand, the longer it takes to navigate the matrix