Gel Electrophoresis and DNA Profiling

Flashcards covering the mechanisms of gel electrophoresis, the functions of various chemical components, and the principles of DNA profiling in forensics.

Gel Electrophoresis

A process that sorts DNA fragments by size by moving them through a gel filter using an electrical current.

Agarose

A jelly-like substance derived from seaweed used to form the gel matrix for separating DNA fragments.

Electrical Current in Electrophoresis

The force that causes negatively charged DNA to migrate toward a positive electrode.

Phosphate Backbone

The part of the DNA molecule that provides its negative charge, allowing it to move toward the positive terminal.

Small DNA Fragments

Fragments that move faster and farther through the gel, forming bands at the bottom.

Large DNA Fragments

Fragments that move more slowly through the gel matrix and form bands at the top.

Ethidium Bromide

A stain used to make DNA bands visible by causeing them to glow under ultraviolet (UV) light.

Buffer Solution (TAE or TBE)

A solution that conducts electricity and maintains a stable pH during the electrophoresis process.

Loading Buffer

A substance mixed with DNA samples that adds density to help them sink into wells and contains dye to track movement.

DNA Size Standard

A reference or ladder used by scientists to estimate the specific sizes of DNA fragments in a gel.

Human DNA Similarity

The fact that humans share approximately $99.9\%$ of their DNA base pairs with one another.

Polyacrylamide

A type of gel used for high-resolution separation of very small fragments, though it is more difficult and toxic to prepare than agarose.

Agarose Concentration

A factor where higher levels improve the separation of smaller fragments, while lower levels are better for separating larger fragments.

Voltage

The electrical setting where higher levels increase DNA migration speed but may reduce the quality and accuracy of fragment separation.

Forensic DNA Verification

The process of minimizing error by labeling samples carefully, wearing protective equipment, repeating tests, and having multiple scientists verify results.