DNA or RNA fragment which is radioactive or chemically labile to detect a specific fragment?
**Core Concept**
The question is asking about a type of probe used in molecular biology to detect a specific DNA or RNA fragment. This probe is typically labeled with a radioactive or chemically labile marker to facilitate detection. The probe is designed to hybridize with the target sequence, allowing researchers to visualize or quantify the presence of the target fragment.
**Why the Correct Answer is Right**
The correct answer is a **probe** that is **radioactively labeled** or **chemically labile**. This type of probe is commonly used in techniques such as Southern blotting, Northern blotting, and in situ hybridization. The radioactive label or chemically labile marker allows the probe to be detected using techniques such as autoradiography or fluorescence.
* The probe is designed to have a high affinity for the target sequence, allowing it to specifically bind to the target fragment.
* The radioactive label or chemically labile marker is typically attached to the probe using a linker molecule, allowing it to be easily detected.
* The use of a probe allows researchers to detect specific DNA or RNA sequences in a complex mixture, making it a powerful tool in molecular biology.
**Why Each Wrong Option is Incorrect**
**Option A:** A _primer_ is a short DNA sequence used to initiate DNA synthesis, but it is not typically radioactive or chemically labile.
**Option B:** A _vector_ is a DNA molecule used to clone a gene of interest, but it is not typically used to detect a specific DNA or RNA fragment.
**Option C:** An _antibody_ is a protein used to detect specific antigens, but it is not typically used to detect DNA or RNA sequences.
**Clinical Pearl / High-Yield Fact**
When using radioactive probes, it's essential to follow proper safety protocols to minimize exposure to radiation. This includes using lead shielding, wearing gloves, and disposing of radioactive waste properly.
**Correct Answer: C. Probe**