DNA extraction
recap
Safety point
Spill phenol on bare feet (flip flops!)  - goodbye skin
Spill phenol on shoes – maybe stained shoes
Spill phenol on bare legs (shorts)  - goodbye skin
Spill phenol on pants – stained pants
Calculation of DNA concentration
Calculation of DNA concentration
Absorbance coefficient for dsDNA at 260nm = 50
So DNA with an absorbance of 1 at 260nm = 50ug/ml (or 50 ng/ul)
We diluted your DNA 1 in 100
Multiply the A260 by 50 to get concentration of diluted sample
Then multiply by 100 to get concentration of your sample
DNA extraction from plants
Smush (“homogenize”) the cells
Dissolve membranes and solublize DNA in a detergent buffer.
Remove solids with centrifugation
Remove proteins with KOAc
Remove proteins with phenol extraction
Precipitate DNA with alcohol
DNA extraction issues
Homogenization 
 - has to be “just right”
RNA
Hydrodynamic shearing
- treat it gently