The answer is 20. Duplicated chromosome has two sister chromatids, identical copies of the chromosome. These two chromatids are joined at the region called centromere. Therefore, one duplicated chromosome has one centromere and two sister chromatids. If there are 20 duplicated chromosomes in a cell, there will be 20 centromeres.
The biggest airlines flying to United States: American Airlines flights to United States, Delta flights to United States, Southwest Airlines flights to United States. Regions in the USA - United States. Airlines flying to the USA - United States - by city.
In the United States, domestic United Airlines flights typically operate from one of the airline's eight American hubs. The largest hubs are at Chicago's O'Hare International Airport (ORD), which also serves as the company's headquarters, and Houston's Bush Intercontinental Airport (IAH).