Edvotek Europe

• Introduction
• Load gels
• Electrophoresis
• Analyse results
What are we doing today?

Why study DNA?

Ready to load kits
• S51 Whose DNA Left Behind?
– Dye based electrophoresis
– Quick - no staining required
– Colourful result!

Health & safety
• No toxic chemicals
• Safe solutions and reagents used in place of research materials

Your crime to solve

Lisa’s saxophone has been stolen!

Lisa’s room.
Blood found on the saxophone case.
The Scene of the
Crime

Suspect 1-
Homer Simpson

Suspect 2-
Krusty the Klown

Compare samples
• Use electrophoresis
• Micropipette to load samples
• Electrical current will separate by size
• Pattern is DNA fingerprint

Gel casting

Running buffer
TAE buffer
• 20ml 50x buffer to 1 litre with water
• Distilled water ideal but tap ok
• Can be reused a few times
• Store unused for future use ok

Agarose
0.8% Agarose
• 3g in 375 ml dilute buffer
• Melt in microwave/autoclave
• Pour when hand hot

Agarose
• Store gels for 1-2 weeks in fridge wrapped in cling film or plastic bag
• Keep any left over gels and remelt next time

The experiment

Prepare gel

Dry loading
• Load gel dry not through buffer!
• Do not puncture bottom of well
• Change tips between each sample

Gel Loading
Load 40  l of each sample into the wells
A B C D E F
Crime
Scene
Suspect 1
Homer
Suspect 2
Krusty

Run gels
• Put on lid and attach to power supply
• Run for 15-20 minutes at 150 volts
• Or 75 volts for 30-40 minutes
• Check for bubbles at electrode

What is DNA fingerprinting?

DNA fingerprint
• Get DNA from someone
• Cut it up with enzymes
• Separate different size bits on a gel
• Pattern is a DNA fingerprint

Get some DNA

DNA is very long
• 2 metres per cell!
• 3 billion letters long (ACTG)
• Like a piece of string

• Cut with scissors

Where to cut?
• Decided by combination of letters
GTTAAC is cut by one sort of enzyme
TTAA cut by a different sort

Real enzymes

Separate on gel
• Made of seaweed - agarose
• Different size pieces move through mesh - like a sieve
• Small move quicker than big
• Called DNA electrophoresis !

big medium small move by size

Analyse results
Lanes 1 & 2- Crime Scene DNA
Lanes 3 & 4 Lanes 5 & 6
Suspect 1- Homer Suspect 2- Krusty

1
2
3
Result
CS S1 S2
A B C D E F

Time to make the arrest

Thank you
• DNA experiments can be carried out easily
• Fun and relevant to wider world
• Promote understanding