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DNA hybridisation is a molecular technique used to determine the evolutionary relationships between species - VCE - SSCE Biology - Question 6 - 2017 - Paper 1
Question 6
DNA hybridisation is a molecular technique used to determine the evolutionary relationships between species. DNA is extracted from each species and cut into fragment... show full transcript
Worked Solution & Example Answer:DNA hybridisation is a molecular technique used to determine the evolutionary relationships between species - VCE - SSCE Biology - Question 6 - 2017 - Paper 1
Step 1
Outline the steps involved in the DNA hybridisation technique following the extraction and cutting of DNA.
Answer
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Extraction of DNA: Collect tissue or cells from the organisms of interest. Use chemical methods to break down cell membranes and release DNA from the nucleus into solution.
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Purification of DNA: Remove proteins and other cellular debris by using filtration and/or precipitation methods. This provides a clean sample of DNA for further analysis.
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Cutting of DNA: Utilize restriction enzymes to cut the DNA at specific sequences, generating smaller DNA fragments that can be hybridised with complementary strands.
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Denaturation: Heat the DNA fragments to separate the strands, creating single-stranded DNA (ssDNA) needed for hybridisation.
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Hybridisation: Combine the ssDNA from different species under controlled conditions. The complementary DNA strands will bind together, forming duplexes at specific temperatures.
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Detection: Utilize techniques such as gel electrophoresis or fluorescent labeling to visualize and analyze the hybridised DNA, determining the degree of similarity or differences among species.
Step 2
How does the technique of DNA hybridisation enable scientists to determine the evolutionary relationships between species?
Answer
DNA hybridisation allows scientists to compare the genetic material of different species. By measuring the degree of hybridisation (e.g., how well DNA from different species pairs together), researchers can infer evolutionary relationships. A higher level of hybridisation indicates a closer evolutionary relationship, as the DNA sequences are more similar due to common ancestry. Conversely, lower hybridisation suggests more distant relationships, reflecting greater divergence in their evolutionary paths.