Question 8 Listen In the following questions arrows are used to represent primers. The arrow head is the 3' end of the primer and the other end of the arrow represents the 5' end. Which of the following represents the orientation of primers in a PCR reaction. (The DNA to be amplified is between the arrows) a) b) ↑ c) ↑ ↑

Quinolone antibiotics treat bacterial infections by blocking the activity of topoisomerase. Why does this treatment work? Explain what occurs at the molecular level.

What are Okazaki fragments and how they are formed?

Genetics in Practice case studies are critical-thinking exercises that allow you to apply your new knowledge of human genetics to real-life problems. Case study Michelle was a 42-year-old woman who had declined counselling and amniocentesis at 16 weeks of pregnancy but was referred for genetic counseling after an abnormal ultrasound at 20 weeks of gestation. After the ultrasound, a number of findings suggested a possible chromosome abnormality in the fetus. The ultrasound showed swelling under the skin at the back of the fetuss neck; shortness of the femur, humerus, and ear length; and underdevelopment of the middle section of the fifth finger. Michelles physician performed an amniocentesis and referred her to the genetics program. Michelle and her husband did not want genetic counseling before receiving the results of the cytogenetic analysis. This was Michelles third pregnancy; she and her husband, Mike, had a 6-year-old daughter and a 3-year-old son. At their next session, the counselor informed the couple that the results revealed trisomy 21, explored their understanding of Down syndrome, and elicited their experiences with people with disabilities. She also reviewed the clinical concerns revealed by the ultrasound and associated anomalies (mild to severe intellectual disability, cardiac defects, and kidney problems). The options available to the couple were outlined. They were provided with a booklet written for parents making choices after the prenatal diagnosis of Down syndrome. After a week of careful deliberation with their family, friends, and clergy, they elected to terminate the pregnancy. Should physicians discourage a 42-year-old woman from having children because of an increased chance of a chromosomal abnormality?