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.
Logan is the largest airport in New England and 18th busiest airport in the United States, with 31.6 million total passengers in 2014. The airport serves as a focus city for JetBlue Airways, who carries out the largest operations from Logan International Airport. The regional airline Cape Air and commuter airline PenAir all carry out hub operations from Boston.