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 double-stranded DNA to around 90 °C. This high temperature causes the hydrogen bonds between the DNA strands to break, resulting in the separation of the two strands.
Step 2
Cool to approximately 50 °C to anneal/attach primers
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After the strands are separated, the temperature is lowered to approximately 50 °C. At this temperature, short segments of DNA known as primers can bind, or anneal, to the specific target sequences on the single-stranded DNA.
Step 3
Heat to approximately 72 °C for DNA polymerase to copy strands
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Next, the temperature is increased to about 72 °C, the optimal temperature for the heat-stable DNA polymerase (such as Taq polymerase). This enzyme then extends the primers, synthesizing new strands of DNA complementary to the target sequences.
Step 4
Repeat cycle
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This process of heating and cooling is repeated for multiple cycles, typically 25-35 times. Each cycle doubles the amount of DNA, amplifying the desired sequence exponentially.
