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.
Here are the 9 U.S. carriers that made Skytrax's World's Top 100 Airlines in 2015. 1. Virgin America (26th overall) Nabbing the top spot among domestic carriers is Virgin America, the U.S. wing of Richard Branson's beloved travel brand.