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What is a DNA probe? DNA probes are used to detect specific base sequences of DNA - AQA - A-Level Biology - Question 8 - 2019 - Paper 2
Question 8
What is a DNA probe? DNA probes are used to detect specific base sequences of DNA. The process is shown in Figure 6.
Worked Solution & Example Answer:What is a DNA probe? DNA probes are used to detect specific base sequences of DNA - AQA - A-Level Biology - Question 8 - 2019 - Paper 2
Step 1
Step 2
Describe how the DNA is broken down into smaller fragments.
Answer
DNA is broken down into smaller fragments through the activity of restriction endonucleases. These enzymes cut the DNA at specific base sequences, effectively breaking the phosphodiester bonds between nucleotides. This process can also occur at recognition sites or via the use of specific enzymes.
Step 3
The DNA on the nylon membrane is treated to form single strands. Explain why.
Answer
The DNA is treated to form single strands so that the DNA probes can bind, attach, or anneal effectively. Single-stranded DNA allows for the formation of complementary base pairs with the probes, facilitating the detection of specific sequences.
Step 4
Lane 1 of Figure 7 enabled the size of the different viral fragments to be determined. Suggest and explain how.
Answer
Lane 1 contains DNA fragments of known sizes, which serve as a reference for comparing the sizes of the viral DNA fragments in the other lanes. By comparing the positions of the viral bands to the known sizes in Lane 1, the sizes of the fragments can be accurately determined.
Step 5