Capillary Electrophoresis for DNA Analysis

A complete set of vocabulary flashcards covering the history, mechanics, instrumentation, and components of capillary electrophoresis in forensic DNA analysis.

Electrophoresis

A process for separating charged molecules based on movement through a medium under the influence of an applied electric field.

F.F. Reuss

The Russian scientist who, in 1807, observed the migration of particles in an electric field.

Arne Wilhelm Tiselius

A Swedish chemist who, in 1930, developed a method for separating proteins in suspension using electric current; he was later awarded the Nobel Prize in Chemistry in 1948.

Capillary Electrophoresis (CE)

Introduced to forensic labs in the mid-1990s, this is currently the method of choice for amplified DNA separation in forensic science.

Formamide

A chemical mixed with amplified DNA samples and an internal size standard; samples are heated and snap-cooled in its presence to ensure DNA remains single-stranded.

Electrokinetic injection

The process of loading negatively charged DNA into a capillary via electromotive force as current flows from the cathode to the anode.

Cathode

The negative pole for electrical current, composed of platinum, where the DNA sample is introduced at the start of the capillary.

Anode

The positive pole for electrical current, composed of platinum, located at the end of the electrophoresis system.

Silicon coating

A coating on the inner walls of the thin capillaries that provides resistance to DNA fragments to optimize separation.

Sieving Medium

A performance-optimized polymer that dynamically coats the capillary wall to control electroosmotic flow, aid allele sizing, and provide a highly denaturing environment.

$$60^{\circ}\text{C}$$

The operating temperature for electrophoresis used to minimize the formation of hybrid structures that could negatively impact the separation of STR fragments.

Inversely proportional

The relationship between the speed of a DNA fragment through the capillary and its molecular weight; larger fragments move more slowly.

Fluorophores

Dyes used in DNA analysis that fluoresce in the visible region of the spectrum, specifically between $400-600\text{nm}$.

Diffraction grating

A component that separates the fluorescence of each dye before it is captured by the CCD camera.

Charge coupled device (CCD)

A camera system that captures the fluorescence emitted by dye-tagged DNA products after excitation by a laser.

Polyimide

The material used for the outer coating of a fused silica capillary, providing physical strength and flexibility.

Autosampler

A component that holds the sample tray and automatically moves to align the plates or reservoirs with the capillaries for injection.

Syringe

A part of the gel block region that stores polymer between runs and generates the force required to fill the capillary.

$$50\,\mu\text{m}$$

The typical internal diameter of the fused silica capillary tube used for DNA separation.

Argon ion laser

A laser with a wavelength of $488\text{nm}$ used for excitation of fluorescently labeled DNA fragments.