Lecture4 - Electrophoresis in practice Gel electrophoresis...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Physical Chemistry Lecture 4 Electrophoresis and light scattering Motion of charged particles In an electric field E a charged particle ( Ze ) moves, the force being proportional to the electric field (for an isotropic medium) The movement is resisted by the viscous drag of the fluid Drag force is proportional to the speed At steady state, the molecule moves with a speed determined by the balance of the drag and electric forces E f Ze v F F state steady At v f F ZeE F ss viscous electric viscous electric Electrophoretic mobility The proportionality coefficient, , between steady-state speed and electric field is the electrophoretic mobility Assumption of a spherical particle of radius r gives an equation for Friction coefficient from Stokes-Einstein theory Depends on charge on particle Depends on “size” of particle Depends on viscosity of the medium Difficult to make quantitative Ionic environment Reduction of ef ective charge by bond ions Reduction of electric field by local ions that also contribute to the electric field Viscous ef ect of oppositely charged particles movement in the opposite direction in the field – electrophoretic ef ect Effects of shape Used as a semiquantitative tool Mobility is directly proportional to Z Mobility is inversely proportional to the friction coefficient E f Ze E v r Ze  6 Electrophoresis in practice Gel electrophoresis Uses an acrylamide or agarose gel Apply electric field for a given time After electrophoresis, the gel is visualized with a stain Various dyes can be added Fluorescent molecules can be
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 3

Lecture4 - Electrophoresis in practice Gel electrophoresis...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online