Random Amplified Polymorphic DNA (RAPD): What does the RAPD method primarily reveal or assess in genetic analyses?
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AStimulate production of sense RNA to compensate for gene loss
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BActivate expression of all genes in a biochemical pathway
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CEliminate expression of all genes in a biochemical pathway
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DReveal intra-specific variation and diversity between species using random primers
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EQuantify absolute transcript copy numbers in single cells
Answer
Correct Answer: Reveal intra-specific variation and diversity between species using random primers
Explanation
Introduction / Context:Random Amplified Polymorphic DNA (RAPD) is a PCR-based marker technique that uses short arbitrary primers to amplify anonymous regions across the genome. The presence or absence of bands reflects DNA polymorphisms and is widely used for diversity analysis, fingerprinting, and preliminary mapping.
Given Data / Assumptions:
- Short, arbitrary primers (usually 10-mers) are used.
- No prior sequence information is required.
- Banding patterns differ among genotypes due to polymorphisms at primer binding sites.
Concept / Approach:RAPD exploits random priming under low stringency. Single nucleotide changes, insertions/deletions, or rearrangements at primer sites alter amplification, generating polymorphic bands. These patterns help assess intra-specific variability and, to a lesser extent, inter-specific relationships. RAPD does not manipulate gene expression; it is a genotyping tool.
Step-by-Step Solution:
Recognize RAPD as a PCR genotyping, not gene regulation, method.Link random primers to polymorphic banding patterns on gels.Interpret band presence/absence as genetic similarity or divergence.Choose the option describing diversity and variation assessment.Verification / Alternative check:Cluster analyses (e.g., UPGMA) built from RAPD band matrices routinely recover known relationships among cultivars or populations, validating its use for diversity studies.
Why Other Options Are Wrong:
- Options about activating or eliminating pathway expression describe functional genomics interventions, not RAPD.
- Absolute transcript quantification requires qPCR/RT-qPCR, not RAPD.
Common Pitfalls:Overinterpreting RAPD without replication; reproducibility can be sensitive to PCR conditions. Use multiple primers and technical repeats to stabilize inferences.
Final Answer:Reveal intra-specific variation and diversity between species using random primers