Crime Scene Investigation: Cindy was attacked by a masked assailant but she managed to scratch him and get away. Three suspects were apprehended and their DNA samples were cut by the same restriction enzyme and then run through a gel. 1. Whose DNA matches the skin under Cindy's fingernails? 2. Why do some DNA piecestravel farther in the gel than others? 3. Why is important to use the same type of restriction enzyme when cutting all the DNA samples? Skin undem Fingernail Cindy's DM Suspect X Suspect Y Suspect Z

During proofreading, which of the following enzymes reads the DNA? primase topoisomerase DNA pol helicase

n gel electrophoresis of DNA, the different bands in the final gel form because the DNA molecules _______. a. are from different organisms b. have different lengths c. have different nucleotide compositions d. have different genes

Chemical analysis shows that a nucleic acid sample contains A, U, C, and G. Is this DNA or RNA? Why?

Match the method with the appropriate enzyme. _____ PCR a. Taq polymerase _____ cutting DNA b. DNA ligase _____ cDNA synthesis c. reverse transcriptase _____ DNA sequencing d. restriction enzyme _____ pasting DNA e. DNA polymerase (not Taq)

DNA replication requires ________ . a. DNA polymerase c. primers b. nucleotides d. all are required

Cloning Genes Is a Multistep Process In cloning human DNA, why is it necessary to insert the DNA into a vector such as a bacterial plasmid?

DNA replicates by which of the following models? a. conservative b. semiconservative c. dispersive d. none of the above

The initial mechanism for repairing nucleotide errors in DNA is _____. a. mismatch repair b. DNA polymerase proofreading c. nucleotide excision repair d. thymine dimers

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?