DNA EXTRACTIONHow does it actually work?

Cell Lysis

Lysis buffers are typically detergents such as sodium dodecyl sulfate (SDS)

What happens if you add dish soap to a frying pan with water that has a layer of grease on top?

Lysis Cont’d

Another analogy: popping a water balloon When you pop a

balloon, it is like lysing a cell

When the balloon is popped, all of the contents are released

Lysis Cont’d

So what actually happens?

Detergents disrupt lipid-lipid interactions compromising cell membrane integrity

Membrane is destroyed or becomes “leaky” depending on lysis buffer

Wash Stage

The next stage typically involves solutions to remove excess salts and impurities

Additionally, proteases, Rnases, etc. are often added to remove proteins (e.g., histones), RNA, etc.

Wash Cont’d

The wash solution (though separate solutions are sometimes used before) also adjusts pH

At low pH, DNA binds to a column Historically made of silica—a combination of

salts, silica and low pH create conditions that attract DNA

Elution

Elution is a fancy term for release of DNA from column

Water or TE (or other elution buffer) has a neutral or alkiline pH, leading to release of DNA

QIAGEN Kit

A few differences: Column properties

differ: lysing action Column

proprietary; not the traditional silica column