A(n) is a site within a chromosome that serves as the starting point for DNA synthesis. Here, the two DNA strands unwind, and replication proceeds outward in opposite directions from this site. This provides an opening called a(n) that forms two .

Nasa scientists must work together to make sure that everything is correct and accounted for when launching a shuttle. besides a physicist, what other type of scientist would be in making sure that the shuttle has the appropriate type and amount of fuel to reach its destination?