Genetics: Analysis of Genes and Genomes: Keyword Hot Links for chapter 16

Each mitochondrion contains about 3000 different proteins and about 5 copies of its own circular DNA. The mitochondrial DNA itself encodes only 13 proteins. The others are encoded in nuclear genes and imported from the cytoplasm. Perhaps 20–30 percent of all proteins encoded in a typical cell are destined for the mitochondria. Little wonder that more than 50 inherited diseases affect mitochondrial function. These affect approximately 4,000 children born in the United States each year. For more on the diversity of types of mitochondrial diseases, their symptoms, and their treatment, consult this keyword site.

The skeletons of six adults and three children were found in a shallow, unmarked grave near Ekaterinburg, Russia, in 1979, but remained hidden until July 1991 when they were revealed under the openness policy (glasnost) of Mikhail Gorbachev. The remains have been positively identified as those of Tsar Nicholas II, Tsarina Alexandra, and their daughters Olga, Tatiana, and Anastasia, who had been killed by a firing squad in the basement of a merchant's house and their bodies dumped in a pit north of the city. The other skeletons were those of Anna Demidova, the Tsarina's lady-in-waiting; Eugene Bodkin, the family's physician; Ivan Kharitonov, their cook; and Alouzy Trupp, the Tsar's valet. The remains of Marie and Alexei, afflicted with hemophilia, were never found and are believed to have been burned. How were the remains identified? By mitochondrial DNA typing, which you can learn about at this keyword site.

Amniocentesis for the prenatal diagnosis of chromosome disorders is usually performed between 15 and 18 weeks after a woman's last menstrual period. A somewhat different procedure called chorionic villus sampling CVS can be carried out earlier in pregnancy, usually between 10 and 12 weeks after a woman's last menstrual period. At this keyword site you can find a nontechnical description of CVS and a discussion of its uses and potential dangers. Write a brief report about the procedure itself, explain its purpose, and describe which women should, or should not, consider the procedure in their own pregnancy.