ZOO 232Homework 2.doc

ZOO 232 Homework 2 Name Date Please answer the following questions from your textbook (total 10 pts). Due: Feb 1, 2010 Chapter 13, Pg. 262 Applied Question 1 Pg. 262 Applied Question 2. Your answers should be based on the information in the provided chart. Pg. 264 A Second Look. Questions 1 and 2 only. Chapter 18, Pg. 373 Applied Question 4 ZOO 232 Homework 2 Name Date Chapter 13, p. 262: Applied Question #1 For a chromosome to carry information and withstand the forces of cell division it must include: A centromere ? largest constriction of the chromosome; the location where spindle fibers attach when the cell divides; made up of CENP-A molecules and alpha satellites Without a centromere, the chromosome will vanish from the cell as soon as division begins because there is no way for it to attach to the spindles. Telomeres ? the tips of the chromosome; many repeats of the sequence TTAGGG; in most cell types, they shorten with each mitotic cell division Origin of replication sites ? location where replication forks begin to form These structures enable the chromosome to replicate and remain intact. The protein encoding genes and their controls are essentially just informational cargo. (Answers derived from text on page 240 of the ZOO 232 textbook, Human Genetics.) Chapter 13, p. 262: Applied Question #2 Karen Martini has a lower risk of having a child with Down syndrome. Although she is older than Suzanne, she does not have any family history of Down syndrome or any other chromosomal condition. Suzanne, on the other hand, does. She has a son with trisomy 21 Down syndrome. The risks in the right hand column are higher because they include many conditions of aneuploid, whereas the middle column includes only the risks for trisomy 21. According to the chart, since Alice is 40 years old, her unborn child?s risk for any aneuploid is 1 in 66, which is greater than 1 percent. Her unborn child?s risk of trisomy 21, however, is 1 in 106 ? a little under a 1% chance. This may be how Alice and her partner misinterpreted the statistics. A woman at age 40 has a 1 in 106 chance of her child having trisomy 21, whereas the same woman at age 45 faces a 1 in 30 chance. Her risk approximately triples in five years? time. (Answers derived from chart on page 262 of the ZOO 232 textbook, Human Genetics.) Chapter 13, p. 264: A Second Look Question #1 Esteban and Maribella have insertional translocation. This is a rare type where a part of one chromosome inserts into a nonhomologous chromosome. In both of their cases, their normal chromosome 10 had an extra bit of chromosome 17 stuck into it. (Answers derived from text on page 239 and page 257 of the ZOO 232 textbook, Human Genetics.) Chapter 13, p. 264: A Second Look Question #2 Esteban and Maribella?s father, Andre, has an unusual arrangement of genetic material; however, since he has the normal amount of chromosomal material (no extra or missing bits of any chromosome), he does not have any symptoms resulting from his abnormal chromosomes. (Answers derived from text on page 239 of the ZOO 232 textbook, Human Genetics.) Chapter 18, p. 373: Applied Question #4 The von Hippel-Lindau gene is an oncogene because it causes overexpression of a transcription factor. This overexpression causes tumors to form in the kidneys, adrenal glands, and blood vessels. (If the von Hippel-Lindau gene were a tumor suppressor, cancerous tumors/cells would only result from the inactivation or deletion of that gene.) (Answers derived from text on page 354 of the ZOO 232 textbook, Human Genetics.)