Download tools and techniques

DNA Fingerprinting
TOOLS AND TECHNIQUES
Intoducing the microLiter!
 A TINY amount…a millionth of a Liter
 Very difficult to measure because it is SOOO small
 Incredibly accurate when measured correctly
 Tools that measure these amounts are therefore INCREDIBLY
expensive…be VERY careful with them!!!
 If a milliliter (mL) is 1/1000 of a Liter…
 A microliter (μl) is 1/1000 of a millileter (mL)
 The greek letter “mu” is used to represent micro (μ)
 Let’s PRACTICE 
 Work through the second page of the packet
“DNA Fingerprinting – Practice Worksheet”
The TOOLS
 DNA Fingerprinting makes use of tools that can work
with incredibly SMALL volumes
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We only need a very small sample of DNA
We can run hundreds or thousands of samples at once in small
spaces
We can be INCREDIBLY accurate and precise
We can use robotic assistance to run the full analysis
The Micropipette
 Are like a normal pipette…but
better 
 They can hold incredibly small
amounts of liquid with
incredibly high accuracy and
precision
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This makes them VERY
expensive!!!
 Two types that we will use:
 P20: Can hold up to 20 μl
 P200: Can hold up to 200 μl
Draw and label a picture to refer back to:
Setting the Micropipette
 Each micropipette has a dial for its particular volume
maximum
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NEVER set the dial above the MAXIMUM listed, this will
damage the micropipette
For a p20…NEVER set above 20
 The three numbers represent the three place values
 Starting with the largest POSSIBLE place value
 Let’s PRACTICE with the second half of practice
worksheet
Techniques for Using Tips
 NEVER TILT THE PIPETTE!!!
 NEVER USE A NAKED PIPETTE!!!
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We use tips to hold liquid, not the pipette itself
Liquids can actually damage (very severely) the internal parts
 To pick up a tip, push the pipette into the tip holder
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ALWAYS keep the tip box COVERED
This keeps out contaminants
 After using ANY liquid, we will switch tips
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This will also help minimize the risk of contamination through
mixing of samples
 To eject a tip, push down on the SIDE button
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This is attached to the metal rod that will push down on the tip
Always eject tips into a WASTE BIN
Techniques for using a Micropipette
 Push the PLUNGER to the FIRST Stop
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DO NOT GO FURTHER THAN THE FIRST STOP
We must create a vacuum in order to pick up liquid
 While holding it down, insert the tip into your liquid
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DO NOT LET GO UNTIL YOU ARE IN LIQUID
This will pick up air, not the liquid
 Release the plunger to pick up the liquid
 To eject, move the tip into the desired container
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Hold the tip against the inside surface of the container you wish to
eject into
Push the PLUNGER to the SECOND Stop to eject ALL liquid
 Let’s practice! 
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Get a pipette each and practice picking up and ejecting a tip, and
pushing the plunger to the FIRST and SECOND stop
Using the microcentrifuge
 NEVER LOAD IT SIDEWAYS
 Like a washing/drying machine, it will spin out of control and
potentially break
 ALWAYS balance the load
 In a 6-holder, this means you can load…
NOT One
 Two
 Three
 Four
 NOT Five
 Six

Balance the epitubes in the rotor
Let’s practice!!!
 Do activity One and Two on the second instructional
handout
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Answer the first two questions by converting
Answer questions 3 and 4: the “Lab Observations”
 We will discuss and answer remaining questions
after returning from break 