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What is a DNA probe? A DNA probe is a short single strand of DNA that is used to detect specific base sequences in a sample - AQA - A-Level Biology - Question 8 - 2019 - Paper 1
Question 8
What is a DNA probe? A DNA probe is a short single strand of DNA that is used to detect specific base sequences in a sample. It is designed to be complementary to s... show full transcript
Worked Solution & Example Answer:What is a DNA probe? A DNA probe is a short single strand of DNA that is used to detect specific base sequences in a sample - AQA - A-Level Biology - Question 8 - 2019 - Paper 1
Step 1
Describe how the DNA is broken down into smaller fragments.
Answer
DNA is broken down into smaller fragments usually by the action of restriction enzymes. These enzymes recognize specific sequences in the DNA and cut the strands at those sites, resulting in smaller, manageable pieces of DNA.
Step 2
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 effectively bind to their complementary sequences. This process enhances the specificity and sensitivity of the detection of the target sequences.
Step 3
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 fragments. By analyzing the position of the viral fragments relative to the known sizes in Lane 1, it is possible to determine the approximate sizes of the viral DNA fragments.
Step 4
Which volunteers had at least one of the viral DNA fragments with 250 base pairs or 535 base pairs?
Answer
To answer this, we need to refer to the data provided in the results section, particularly the volunteers' information where their DNA fragments were analyzed. Volunteers who had fragments of 250 base pairs or 535 base pairs should be listed based on the provided results.