(Reuters) - McDonald's Corp head of U.S. operations, Chris Kempczinski, replaced Steve Easterbrook as chief executive officer of the world's largest fast-food chain on Sunday.Easterbrook was dismissed following a recent consensual relationship with an employee.Kempczinski, 51, takes over the helm four years after joining the company as an executive vice president.Here are some quick fact about the McDonald's new chief:EducationKempczinski has an MBA degree from Harvard Business School (1997)..