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Short tandem repeats (STRs) are short sequences of DNA, usually 2 to 7 base pairs - AQA - A-Level Biology - Question 9 - 2023 - Paper 2
Question 9
Short tandem repeats (STRs) are short sequences of DNA, usually 2 to 7 base pairs. STRs are repeated a number of times, one after another. For example, the STR D5581... show full transcript
Worked Solution & Example Answer:Short tandem repeats (STRs) are short sequences of DNA, usually 2 to 7 base pairs - AQA - A-Level Biology - Question 9 - 2023 - Paper 2
Step 1
Describe how STRs could be removed from a sample of DNA.
Answer
One way to remove STRs from a sample of DNA is by utilizing restriction endonucleases or enzymes. These enzymes can cut the DNA at specific base sequences or pairs associated with the STRs, effectively isolating them from the rest of the genetic material.
Step 2
Explain the importance of knowing these base sequences in PCR.
Answer
Knowing the specific base sequences on either side of the STR is crucial for the PCR process as it allows for the design of primers that are complementary to these sequences. Primers are essential for initiating DNA synthesis. They provide a starting point for the Taq polymerase enzyme to extend the new DNA strand, ensuring that the correct region of the DNA is amplified during the PCR process.