Mitochondria are unusual organelles. They act as the power plants of the cell, are surrounded by two membranes, and have their own genome. They also divide independently of the cell in which they reside, meaning mitochondrial replication is not coupled to cell division.itochondria are unusual organelles. They act as the power plants of the cell, are surrounded by two membranes, and have their own genome. They also divide independently of the cell in which they reside, meaning mitochondrial replication is not coupled to cell division.
U.S. immigration law is very complex, and there is much confusion as to how it works. The Immigration and Naturalization Act (INA), the body of law governing current immigration policy, provides for an annual worldwide limit of 675,000 permanent immigrants, with certain exceptions for close family members.
As of 2013, approximately 11.6 million Mexican immigrants resided in the United Statesâup from 2.2 million in 1980âand Mexicans accounted for 28 percent of the countryâs 41.3 million foreign born. Immigration from Mexico to the United States has gone through four main periods.