Q. Make an instruction execution feasible?

What are the functions that a control unit performs to make an instruction execution feasible? Instruction execution is achieved by executing micro-operations in a specific sequence. For different instructions this sequence can be different. So the control unit should perform two elementary functions: 

• Cause execution of a micro-operation.
• Enable the CPU to execute a proper sequence of micro-operations that is determined by instruction to be executed.

However how are these two tasks achieved? The control unit produces control signals which in turn are responsible for achieving the above two tasks.