ICs are made with transistors. Look at the datasheet of a CD4017 and it shows 5 flip-flops, 10 NAND gates, 1 AND gate, 17 inverters and 1 Schmitt trigger inverter that use hundreds of Mosfet transistors.
you dont need x-tra transistor unless leds arn't bright enough,,
NOTE: you need one flip-flop per "step", so if you want the led's to go 1,,2,,3,,1,,2,,3,, you need 3 flip flops
THe flip flop circuit that I gave you earlier is wrong,....they are BOTH CLOCK circuits.......to make a proper JK-flip flop you need 4-NAND gates
sorry bout that!!!
attached here is the JK flip-flop schematic made up with nand gates,,,,and how to make a NAND gate with transistors and how to wire the flipflops with the timer and leds......