What is chelex beads?
The correct answer and explanation is :
Chelex Beads – Definition and Explanation
Definition:
Chelex beads are chelating ion-exchange resin beads composed of styrene-divinylbenzene copolymers with paired iminodiacetate ions. These beads are commonly used in molecular biology and biochemistry for the rapid and simple extraction of DNA from biological samples by binding and removing divalent metal ions (e.g., Mg²⁺, Ca²⁺) that can degrade DNA.
Explanation (300 words):
Chelex beads, often referred to as Chelex 100 resin, are a specialized type of ion-exchange resin used widely in laboratories for the extraction and purification of nucleic acids, particularly DNA. The resin is composed of styrene-divinylbenzene copolymer beads to which iminodiacetate groups are chemically attached. These functional groups act as chelating agents, meaning they have the ability to bind tightly to metal ions, especially divalent cations like magnesium (Mg²⁺) and calcium (Ca²⁺).
In molecular biology, these metal ions play a crucial role in the activity of nucleases—enzymes that can degrade DNA. By removing these ions, Chelex beads inhibit nuclease activity and thereby protect DNA from degradation during the extraction process. This property makes Chelex a valuable tool for quick and efficient DNA extraction, especially in forensic science, clinical diagnostics, and genetic testing.
The Chelex extraction method typically involves mixing the biological sample (e.g., blood, saliva, or buccal cells) with a suspension of Chelex resin in water or buffer. The mixture is heated to denature proteins and lyse cells, releasing DNA into the solution. The Chelex beads bind divalent ions released during this process, rendering the sample nuclease-inactive. After centrifugation, the supernatant containing the purified DNA is collected for downstream applications like PCR (polymerase chain reaction).
One major advantage of Chelex-based extraction is that it’s quick, inexpensive, and does not require organic solvents or complex procedures. However, the resulting DNA may be single-stranded or less pure compared to other methods, so it is mostly used in applications where high purity is not critical.