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Basic Techniques

Basic Techniques

 
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Bio 420/642
 Molecular Biology
Department of Biological Sciences, Lehman College

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Notebook Keeping
Fluid Measurements
Micropipettes
Pipetting
Graduated cylinders
Microcentrifuge
Sterile technique
Bottle to bottle
Plate to plate
Streaking for single colonies
Solution calculations
Metric system
Quiz

 

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Materials and recipes

 

WEBRESOURCES

Bio-Rad
ATCC
Metric system
Stock Solutions
Company Addresses
Centrifugation
Spectrophotometry
Quantitation of Nucleic Acid Concentration
Disposal of Buffers and Chemicals
Antibiotics
Clean-up for Ethidium Bromide
Cleaning Radiation
Buffers
Phosphate Buffers
Safety Procedures
Equipment
Sterile Technique
Phenol Equilibration

Read:  Notebook Keeping

Fluid Measurements

Micropipettors are the usual instrument for fluid measure in a molecular laboratory. They are used for measuring small volumes in the range of 0.1 to 5000 無. Larger volumes (above 1-5ml are measured with glass or plastic graduated pipettes). Micropipettors and plastic pipettes should not be used with organic solvents, as the plastic  may dissolve. Still larger volumes (>20 ml) should be measured with graduated cylinders. The use of each  of these fluid-handling devices is discussed below.

Micropipettors

These are delicate (and expensive) instruments that require care and maintenance.   They should be checked for accuracy frequently. Common manufacturers are Eppendorf and   Gilson  (Pipetman). Only the use of Pipetman is described here; other brands are similar.

Pipetman come in different sizes with different volume ranges and are used with disposable plastic tips that come in various sizes to match. Accuracy of measurement depends on selection of the appropriate pipettor for your desired measurement. Three such sizes that are commonly in use are:

NAME

RANGE  

DISPOSABLE TIP COLOR

P20

1-20 無

yellow

P200

20-200 無

yellow

P1000

 

200-1000 無

blue

The names are on the end of the plunger.

pipettman.GIF (58164 bytes)tips.GIF (18608 bytes)

The other

There are numbers on the dial which indicate the volume measured. The dial should never be turned beyond the range of the pipettor and a pipettor should not be used outside of its range (listed above). For example, it is inappropriate to use a P200 to measure 17 無 or a P1000 to measure 150 無. The format of the numbers is different on the three different pipettors, so may be somewhat confusing. Compare the tables below to the device and arrive at a set of working rules for dialing volumes for yourself.  Review the Metric system before you start if necessary.

 

On a P20, the following settings indicate the volumes shown:

1 無

10 無

15 無

20.5無

0

1

0

1

0

0

1

5

0

2

0

5

On a P200, the following settings indicate the volumes shown:

20 無

45 無

120 無

200 無

0

2

0

0

4

5

1

2

0

2

0

0

On a P1000, the following settings indicate the volumes shown:

220 無

0.5 ml

720 無

  1 ml

0

2

2

0

5

0

0

7

2