GPIO vs. I2C- another N00B question/ I2C Interrupt Monitoring?

to expand on that:

pi@raspberrypi:~/plc $ python pullup.py
Traceback (most recent call last):
File “pullup.py”, line 7, in
GPIO.setup(27, GPIO.IN, pull_up_down=GPIO.PUD_UP)
ValueError: The channel sent is invalid on a Raspberry Pi