Steve Jobs turned down Tim Cook's liver transplant offer

A new biography of Apple Co-Founder Steve Jobs reveals current Apple CEO Tim Cook offered his boss a piece of his liver.

According to the book, "Becoming Steve Jobs," Cook and Jobs shared a rare blood type, so the two were compatible.

But, Jobs refused Cook's offer in 2009, a decision Cook described to the author as "selfless."

Jobs told Cook, he would never let him do that.

Cook said, "Steve only yelled at me four or five times during the 13 years I knew him and this was one of them."

Jobs eventually received a liver transplant, but died in 2011.