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.
United Airlines is one of the largest air carriers in the world. Based in Chicago, the airline operated 698 aircraft as of October 2012. The airline flies eight different aircraft types, six manufactured by Boeing Company and two by Airbus Industrie. In addition, the airlineâs United Express arm operates 541 aircraft.