Solutions and Dilutions Basic Skills of the Biotechnology Workplace - PowerPoint PPT Presentation

Solutions and Dilutions Basic Skills of the Biotechnology Workplace

What do you know about solutions?

Solution • Solute: the substance being dissolved • Solvent: the substance that dissolves the solute • Concentration of a solution can be expressed as the amount of mass per some unit of volume, for example, g/mL

Common Solution in Biotechnology Agarose Room Solution is Temperature Boiled Until Clear

Agarose Gel

Common Solution in Biotechnology • Agarose solution is used to cast agarose gels for electrophoresis • 0.8% or 1% agarose solutions are commonly used to cast gels for electrophoresis • Agarose gels with higher concentrations ( 2% or 3% ) are used to visualize very small pieces of DNA

Why is the concentration of the gel important? • Incorrect concentrations make it difficult to visualize DNA bands during electrophoresis • Concentration of the gel affects the resolution and separation of DNA fragments

Low Agarose High Agarose Concentration Concentration

Agarose Solution • Solute: Agarose - polysaccharide polymer extracted from seaweed • Solvent: Buffer (either TBE or TAE) - near-neutral pH which allows the DNA to migrate towards the anode (+)

Mass/Volume Concentration Equation 0.8% Agarose 100mL Total Volume _____ g/mL x _____ mL = _____ g of solute concentration volume to be weighed out, desired desired dissolved in the solvent

What do you know about dilutions?

Dilution • Concentrated solutions are “diluted” by adding more solvent • Stock solutions need to be diluted to “working concentrations”

Common Dilution in Biotechnology • Diluting concentrated stock solutions of TBE and TAE buffers used for gel electrophoresis • Buffers resist changes in pH and help preserve the structure and function of molecules dissolved in the buffer

TAE Buffer • TAE buffer (Tris-acetate with EDTA) - used to cast agarose gels and for running buffer during electrophoresis experiments • Commonly shipped as 50X or 20X concentrated • “Working concentration” is 1X

Dilution Equation C 1 V 1 = C 2 V 2 C 1 = concentration of C 2 = desired the concentrated concentration of the stock solution diluted sample V 1 = volume to use of V 2 = desired volume of the stock solution in the diluted sample the diluted sample

C 1 V 1 = C 2 V 2 Dilute 50x TAE buffer to a working concentration of 1X 100 mL Total Volume

Making Agarose Casting an Agarose Gel