In fig, Phi is fixed at 0º. Clashes occur at ALL Psi angles. Phi = 0º is physically

impossible.

#Id: 2475

#Unit 13. Methods in Biology

IEF takes place in a pH gradient and can only be used for amphoteric substances such as peptides and proteins. The charged molecules move toward the anode or the cathode until they reach a position in the pH gradient where their net charges are zero. This pH value is the “isoelectric point” (pI) of the substance.

#Id: 2476

#Unit 13. Methods in Biology

Agarose is one of the components of agar, which is a mixture of polysaccharides isolated from certain seaweeds and usually used at concentrations of between 1% and 3% in labs. 

#Id: 2477

#Unit 13. Methods in Biology

Agarose gels are formed  by suspending dry agarose in aqueous buffer, then boiling the mixture until a clear solution forms. 

#Id: 2478

#Unit 13. Methods in Biology

The most commonly used buffer for separating DNA is TRIS-acetate containing EDTA ( TAE) with a typical pH of 8.3 and used to dissolve the matrix (agarose) as well as the running buffer. 

#Id: 2479

#Unit 13. Methods in Biology

Separation of RNA, TRIS-borate with EDTA ( TBE) is typically used due to superior buffering capacity (beneficial for long run times).

#Id: 2480

#Unit 13. Methods in Biology

TBE gives superior separation of smaller fragments (< 2 kb) in comparison to TAE and is often used for separation of small RNA molecules such as microRNA.