Multiple Choices: At the replication fork, new DNA is synthesized by a:  -RAS-RAF pathway -Transposable element -extracellular matrix -Multi-enzyme complex   and The Chromosomal Theory of Inheritance is credited to two scientists who:  -Developed it before Mendel completed his work -Developed it independently but simultaneously -Developed it as a team -Developed it after Thomas Hunt Morgan completed his work

A proband female with an unidentified disease seeks the advice of a genetic counselor before starting a family. Based on the following data, the counselor constructs a pedigree encompassing three generations: (1) The maternal grandfather of the proband has the disease. (2) The mother of the proband is unaffected and is the youngest of five children, the three oldest being male. (3) The proband has an affected older sister, but the youngest siblings are unaffected twins (boy and girl). (4) All the individuals who have the disease have been revealed. Duplicate the counselors feat

SCIENCE, TECHNOLOGY, AND SOCIETY Imagine that you are a genetic counselor. What advice or suggestions might you give in the following situations? (a) A couple has come for advice because the woman had a sister who died of Tay-Sachs disease. (b) A young man and woman who are not related are engaged to be married. However, they have learned that the mans parents are first cousins, and they are worried about the possibility of increased risk of genetic defects in their own children. (c) A young womans paternal uncle (her fathers brother) has hemophilia A. Her father is free of the disease, and there has never been a case of hemophilia A in her mothers family. Should she be concerned about the possibility of hemophilia A in her own children? (d) A 20-year-old man is seeking counseling because his father was recently diagnosed with Huntingtons disease. (e) A 45-year-old woman has just been diagnosed with Huntingtons disease. She says she will not tell her college-age sons because of the burden it will place on them. Given that the woman, not her sons, is your client, do you have a duty to inform the sons? Explain your reasoning.

The Joneses were referred to a clinical geneticist because their 6-month-old daughter was failing to grow adequately and was having recurrent infections. The geneticist took a detailed family history (which was uninformative) and a medical history of their daughter. He discovered that their daughter had a history of a constant cough and wheeze that was becoming progressively worse, had difficulty gaining weight (failure to thrive), and had an extensive history of yeast infection (thrush) in her mouth. The geneticist did a simple blood test to check their daughters white blood count and determined that she had severe combined immunodeficiency (SCID). The geneticist explained that SCID is an immune deficiency that causes a marked susceptibility to infections. The defining characteristic is usually a severe defect in both the T- and B-lymphocyte systems. This results in one or more infections within the first few months of life that are serious and may even be life-threatening. Based on the family history, it was possible that their daughter had inherited a mutant allele from each of them and therefore was homozygous for a gene that causes SCID. If so, each time the Joneses had a child, there would be a 25% chance that the child would have SCID. Prenatal testing is available to determine whether the developing fetus has SCID. If the Joneses want to be certain that their next child will not have SCID, what types of reproductive options do you think they have?

Mary and Marcie. identical twins, go to the same internist who is also a faculty member at a major medical center. At their last visit, they each received a brochure describing a genetics research program recently launched by the hospital and its affiliated university. Researchers were asking for volunteers to fill out a questionnaire and a consent form, donate a blood sample, and have their medical records encoded and transferred to a database. The goal was to enroll 100,000 participants, and the brochure noted that over 10,000 people had already agreed to participate. The blood sample would be used to extract DNA. which would be encoded with the same number as the medical records. This DNA would be used to search for genes associated with conditions such as arthritis, diabetes, and Alzheimer disease. The idea is that researchers interested in studying arthritis would use the medical records to identify which participants have the condition and then use DNA from those individuals to find genetic similarities that are not present in participants who do not have arthritis. The genetic similarities help identify regions of the genome that contain genes associated with arthritis. These regions can then be studied in detail to identify and isolate genes that may be associated with arthritis and other inflammatory disorders. In exchange for enrolling, participants would be informed about any genetic conditions or predispositions to genetic disease they carry and would receive free access to testing. After discussing the brochure. Mary decided to enroll, but Marcie decided she did not want to do so. She said she did not want to know what diseases she may develop or which disease genes she may carry. At their next annual visit. Marys internist told her that because her questionnaire indicated that some relatives had Alzheimer disease, her DNA was used in a study to identify risk genes. He said she had been identified as a carrier of a gene that greatly increased the likelihood that she would develop Alzheimer disease. The physician told her that age was the greatest risk factor, and while it was not 100% certain she would become a victim of Alzheimer disease, the gene she carries is a factor in 2025% of all cases. Mary asked if there was anything she could do about these findings. The internist told her that exercise, controlling blood pressure and cholesterol levels, as well as participating in mentally challenging activities such as reading or playing a musical instrument may all help reduce her chances of developing this disease. Mary then asked if Marcie was going to be told about Marys genetic risk, and the internist said that he would not tell her. For the next few days. Mary was conflicted about the situation. Marcie was an Identical twin, and If Mary carried a gene predisposing her to Alzheimer disease. Marcie must carry the same gene. Marcie did not exercise with Mary, had high blood pressure, and little interest in reading or social activities. Mary did not know whether she should tell Marcie. If you were advising Mary, what would you say? Should she tell Marcie about the risk? Should she not tell her, but instead try to get Marcie to exercise and be more social? Should Mary ask their internist to talk with Marcie about this?

In Section 12-1, Julie is concerned that she may develop breast cancer, but testing shows that she does not carry the rare high-risk BRCA1 and BRCA2 alleles. What if further testing showed that some of her aunts, her mother, and she carried a common low-risk allele for breast cancer. What would you recommend to Julie if you were her genetic counselor?

Familial retinoblastoma, a rare autosomal dominant defect, arose in a large family that had no prior history of the disease. Consider the following pedigree (the darkly colored symbols represent affected individuals): a. Circle the individual(s) in which the mutation most likely occurred. b. Is the person who is the source of the mutation affected by retinoblastoma? Justify your answer. c. Assuming that the mutant allele is fully penetrant, what is the chance that an affected individual will have an affected child?

Theodor Boveri predicted that malignancies would often be associated with chromosomal mutation. What lines of evidence substantiate this prediction?

Analysis of X-Linked Dominant and Recessive Traits A young boy is color-blind. His one brother and five sisters are not. The boy has three maternal uncles and four maternal aunts. None of his uncles children or grandchildren is color-blind. One of the maternal aunts married a color-blind man, and half of her children, both male and female, are color-blind. The other aunts married men who have normal color vision. All their daughters have normal vision, but half of their sons are color-blind. a. Which of the boys four grandparents transmitted the gene for color blindness? b. Are any of the boys aunts or uncles color-blind? c. Is either of the boys parents color-blind?

Pedigree Analysis Is a Basic Method in Human Genetics Using the pedigree provided, answer the following questions. a. Is the proband male or female? b. Is the grandfather of the proband affected? c. How many siblings does the proband have, and where is he or she in the birth order?