Module 5 Cell Division

3.5.5 page 3

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There is a dramatic increase in the incidences of nondisjunction in female gametes as a woman ages. For example, the chances of having a Down syndrome child at 25 is 1:1500, by age thirty the risk is 1:910, and by the age of 45 it is 1:30 a specific cause for this is unknown.

Given that the oocytes have been suspended in prophase I for so many years, it is likely that the apparatus to complete meiosis properly has deteriorated. New research also indicates that a woman’s womb can becomes less selective for genetically compromised embryos making it more likely to carry an embryo with a genetic disorder to term.

Genetic Testing

You may recall from your studies in unit B the various technologies used to test a fetus for genetic problems. Three common procedures are amniocentesis, cordiocentesis, and chorionic villi sampling. Each differs on when it can be done, which material it tests, and how quickly the answers come back. Each test is the same in terms of what they are looking for: an abnormal number of chromosomes.

Try This

Research the following genetic testing technologies by completing the following table, and share your work with your fellow students and your instructor.

Ethical Concerns

Science is very good at seeking knowledge. However, it is not the role of science or even scientists to decide what should be done with that knowledge. Instead, this role falls on the shoulders of society. What are some ethical concerns that can arise from prenatal genetic testing? What is the tension or debate that focuses on prenatal testing?

Module 5: Lesson 5 Assignment—Stem Cell Research

While some groups within society may object to prenatal tests because of the possible risks to the fetus, or because of the future actions parents may take in their pregnancy, the debate is focused on a possible action. Stem cell research may have greater ethical concerns because of the certain death it causes to the blastocyst from which these cells are taken.