The target sequence in a D can be determined/ identified in Southern blotting by:
Show Hint
Probes are single-stranded nucleic acids labeled with fluorescent or radioactive tags designed to find complementary target sequences during blotting or in situ hybridization.
Step 1: Understanding the Question:
The question asks for the biological tool used in Southern blotting to specifically hybridize with and reveal the presence of a targeted D sequence. Step 2: Key Formula or Approach:
Southern blotting combines agarose gel electrophoresis, transfer to a solid support membrane, and molecular hybridization using labeled single-stranded nucleic acid molecules known as probes. Step 3: Detailed Explation:
• Definition of D Probe: A probe is a single-stranded sequence of D or R (typically 20 to 1000+ nucleotides long) that is complementary to the specific gene or D target sequence under investigation.
• Labeling and Detection: Probes are tagged with radioactive isotopes (such as $^{32}\text{P}$) or fluorophores/enzymes (like digoxigenin or biotin). When applied to the membrane containing immobilized target single-stranded D, the probe selectively hybridizes to its complementary sequence via hydrogen bonding.
• Visualization: Unbound probes are washed away, and the hybrid molecules are detected using autoradiography, chemiluminescence, or fluorescence imaging.
• Roles of Incorrect Options:
• Primer: Short oligonucleotides used to initiate enzymatic synthesis in PCR, not for direct hybridization detection on membranes.
• Promoter: A D regulatory sequence where R polymerase binds to initiate transcription.
• Pribnow Box: A specific consensus D sequence (TATAAT) found in prokaryotic promoter regions around $-10$ position. Step 4: Fil Answer:
A labeled probe is the specific molecule used in Southern blotting to detect target D sequences through complementary base pairing.
