Genetic information in humans can be obtained by DNA profiling - VCE - SSCE Biology - Question 3 - 2012 - Paper 1
Question 3
Genetic information in humans can be obtained by DNA profiling. In DNA profiling, the polymerase chain reaction is used by a scientist to amplify a particular sequen... show full transcript
Worked Solution & Example Answer:Genetic information in humans can be obtained by DNA profiling - VCE - SSCE Biology - Question 3 - 2012 - Paper 1
Step 1
Heat DNA to approximately 90 °C to separate strands
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The first step involves heating the DNA sample to about 90 °C. This high temperature causes the two strands of the DNA double helix to separate, a process known as denaturation.
Step 2
Cool to approximately 50 °C to anneal/attach primers
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Next, the temperature is reduced to approximately 50 °C. At this temperature, short sequences of DNA known as primers can attach to the specific target sequences in the single-stranded DNA.
Step 3
Heat to approximately 72 °C for DNA polymerase to copy strands
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After primer attachment, the temperature is increased to about 72 °C. This is the optimal temperature for the enzyme Taq polymerase, which synthesizes new DNA strands by extending from the primers and creating complementary copies of the target sequences.
Step 4
Repeat cycle
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Finally, the entire process is repeated multiple times (usually 25-35 cycles) to exponentially amplify the target DNA sequence, resulting in a large amount of the particular DNA fragment needed for analysis.
