Biotechnology: Genetic Engineering Techniques (College Board AP® Biology): Exam Questions

A researcher investigated whether a patient carried a genetic mutation linked to a hereditary disease. They used a small DNA sample from the patient and the polymerase chain reaction (PCR).

Which of the following is the most likely predicted outcome from the PCR process?

A restriction enzyme is an enzyme used in biotechnology to cut DNA wherever a specific sequence of bases occurs. A restriction enzyme was used to cut a sample of DNA from a wild boar. The resulting genetic fingerprint can be seen in Figure 1.

Which of the following states the number of times that the enzyme made a cut in the DNA sample?

BRCA1 is a tumor suppressor gene involved in the repair of damaged DNA. In an investigation researchers used PCR to amplify the BRCA1 gene from DNA samples taken from 50 individuals with a family history of breast cancer. After sequencing the amplified gene regions they found that 10 individuals carried mutations associated with an increased risk of cancer.

Which of the following conclusions can be drawn from this study?

The run-off from nitrogen-rich fertilizer applied to farmland creates major ecological problems. Plants such as legumes have symbiotic nitrogen-fixing bacteria which can help them to gain nitrogen from the soil without the need for adding fertilizer. However, these symbionts are not associated with crops such as corn. Scientists have developed a strain of nitrogen-fixing bacteria that can associate with corn roots.

Which of the following describes the method used by the scientists to synthesize this bacteria?

DNA samples were taken from five individuals and analyzed using gel electrophoresis to produce a DNA profile. Figure 1 below shows the results for a single gene.

Which of the following can be concluded from the profile shown in Figure 1?

PCR is a process used to amplify DNA. It is possible to monitor the progress of a PCR reaction using quantitative PCR, or qPCR. qPCR involves the addition of a dye that emits fluorescence, meaning that as DNA is produced, fluorescence increases; this fluorescence can be plotted on a graph known as an amplification curve. The PCR cycle at which fluorescence can be detected above background levels is known as C_q. Figure 1 shows the point at which C_q is reached in PCR reactions that start with different numbers of DNA fragments.

Which of the following correctly describes the data in Figure 1?

Fragile X syndrome is a genetic disorder caused by the presence of an increased number of CGG-CCG repeats in the FMR1 gene. The FMR1 gene is located on the X chromosome.

• Alleles with 55-200 additional CGG-CCG repeats are said to have a premutation status

• Alleles with more than 200 additional CGG-CCG repeats can cause Fragile X syndrome

Figure 1 shows the results of a gel electrophoresis test used to determine whether an individual has any alleles for Fragile X syndrome. Note that individual 2 is a biological female with two unmutated copies of the FMR1 allele.

Which of the following contains a correct conclusion from Figure 1?

There are many factors that can influence the efficiency of the bacterial transformation process. A group of researchers studied the impact of bacterial cell storage method on transformation efficiency using the following procedure:

• bacterial cells were stored in a freezer set to a temperature (-4 °C, -20 °C or -70 °C) for a set period of time (1 hour, overnight, 1 day, 2 days, 3 days, 5 days, 7 days, 10 days, 15 days or 20 days)

• bacterial cultures were removed from the freezer and allowed to return to room temperature

• a plasmid vector, specifically a pAHC25 plasmid, was used to transfer DNA into bacterial cells

• the researchers assessed transformation efficiency by looking at the number of transformed cells.

Their results are shown in Figure 1 below.

Which of the following claims is most likely to be appropriate for the data in Figure 1?