A covalent bond is a chemical bond that occurs when two or more atoms share electrons. The sharing of electrons helps complete the outer shell, or valence shell, of both atoms. The sharing of electrons creates a stable balance of attractive and repulsive forces between atoms.

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#Unit 13. Methods in Biology

In ZE a homogeneous buffer system is used over the whole separation time and range so as to ensure a constant pH value.

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#Unit 13. Methods in Biology

In ITP, the separation is carried out in a discontinuous buffer system. The ionized sample migrates between a leading electrolyte with a high mobility and a terminating – sometimes called trailing – ion with a low mobility, all of them migrating with the same speed.

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#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.

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#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. 

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#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. 

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#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.