Figure Detail. As mentioned, sickle-cell anemia is the result of a change in a single nucleotide, and it represents just one class of mutations called point mutations. Changes in the DNA sequence can also occur at the level of the chromosome, in which large segments of chromosomes are altered.he result is the deletion of a DNA sequence in one chromosome, and the insertion of a DNA sequence in the other chromosome. Â© 2014 Nature Education Adapted from Pierce, Benjamin. Genetics: A Conceptual Approach, 2nd ed.
Also established in 1984, the Texas Division of Southwestern Bell Telephone, with headquarters at Dallas, became one of the largest nongovernmental employers in the state, serving 6.2 million customers in 549 Texas communities.
The first telephone exchange in the United States opens in New Haven, in 1878, under license from Bell Telephone. Within a few years, licensed telephone exchanges open in every major city in the country. January 14, 1879, Bell demonstrates the telephone for Queen Victoria..Henry recognizes the significance of Bell's work and offers him encouragement. In September 1875, he began to write the specifications for the phone. 14 february 1876, Bell's telephone patent application is filed at the United States Patent Office.