ATI TEAS (Test of Essential Academic Skills) Version 7ScienceHard
A technician is performing a diagnostic test that requires the separation of charged molecules, such as DNA fragments or proteins, based on their size and electrical charge. Which laboratory technique would be most appropriate for this purpose?
- ASpectrophotometry
- BChromatography
- CCentrifugation
- DGel Electrophoresis
Show answer & explanationAnswer & explanation
Correct answer: D. Gel Electrophoresis
Gel electrophoresis is a standard laboratory technique used to separate macromolecules like DNA, RNA, and proteins based on their size and electrical charge. Charged molecules migrate through a gel matrix when an electric field is applied, with smaller, more highly charged molecules moving faster.
Why the other options are wrong
- A. Spectrophotometry measures the absorbance or transmission of light through a sample to quantify concentrations, not to separate molecules by size and charge.
- B. Chromatography separates components of a mixture based on differential partitioning between a stationary phase and a mobile phase, which can involve size or charge, but 'gel electrophoresis' is more specific and direct for separating charged macromolecules by size and charge.
- C. Centrifugation separates substances based on density by spinning them at high speeds, not primarily by size and electrical charge for molecular separation.
Gel Electrophoresis
A laboratory technique used to separate DNA, RNA, or protein molecules based on their size and electrical charge by applying an electric current to a gel matrix.
- Nucleic acids migrate towards the positive electrode (anode) due to their negative charge.
- Smaller molecules move faster and further through the gel than larger ones.
- Commonly used for DNA fingerprinting, gene analysis, and protein analysis.
Memory trick: Separate Samples, See Sizes, Sense Charges.